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<!-- DFIN New ActiveDisclosure (SM) XBRL Linkbase Document - http://www.dfinsolutions.com/ -->
<!-- Creation Date :2022-11-08T21:07:10.8981+00:00 -->
<!-- Copyright (c) 2022 Donnelly Financial Solutions, Inc. All Rights Reserved. -->
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    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="dei_EntityAddressCityOrTown_lbl" xlink:role="http://www.xbrl.org/2003/role/label">Entity Address, City or Town</link:label>
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    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="dei_EntityExTransitionPeriod_lbl" xlink:role="http://www.xbrl.org/2003/role/label">Entity Ex Transition Period</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="dei_EntityExTransitionPeriod_lbl" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Entity Ex Transition Period</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_FairValueDisclosuresAbstract_lbl" xlink:role="http://www.xbrl.org/2003/role/label">Fair Value Disclosures [Abstract]</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_EarningsPerShareAbstract_lbl" xlink:role="http://www.xbrl.org/2003/role/label">Earnings Per Share [Abstract]</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_FairValueInputsLevel1Member_lbl" xlink:role="http://www.xbrl.org/2003/role/label">Fair Value, Inputs, Level 1 [Member]</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_FairValueInputsLevel1Member_lbl" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Level 1</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_ScheduleOfAccruedLiabilitiesTableTextBlock_lbl" xlink:role="http://www.xbrl.org/2003/role/label">Schedule of Accrued Liabilities [Table Text Block]</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_ScheduleOfAccruedLiabilitiesTableTextBlock_lbl" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Schedule of Accrued Liabilities</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_ResearchAndDevelopmentExpensePolicy_lbl" xlink:role="http://www.xbrl.org/2003/role/label">Research and Development Expense, Policy [Policy Text Block]</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_ResearchAndDevelopmentExpensePolicy_lbl" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Research and Development Costs</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_NetCashProvidedByUsedInFinancingActivitiesAbstract_lbl" xlink:role="http://www.xbrl.org/2003/role/label">Net Cash Provided by (Used in) Financing Activities [Abstract]</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_NetCashProvidedByUsedInFinancingActivitiesAbstract_lbl" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Financing activities</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="clsd_RisksAndUncertaintiesPolicyTextBlock_lbl" xlink:role="http://www.xbrl.org/2003/role/documentation">Effects of COVID-19.</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="clsd_RisksAndUncertaintiesPolicyTextBlock_lbl" xlink:role="http://www.xbrl.org/2003/role/label">Risks And Uncertainties Policy [Text Block]</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="clsd_RisksAndUncertaintiesPolicyTextBlock_lbl" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Effects of COVID-19</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsOutstandingWeightedAverageRemainingContractualTerms_lbl" xlink:role="http://www.xbrl.org/2003/role/label">Share-Based Compensation Arrangement by Share-Based Payment Award, Equity Instruments Other than Options, Outstanding, Weighted Average Remaining Contractual Terms</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsOutstandingWeightedAverageRemainingContractualTerms_lbl" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Weighted average remaining life of warrants</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="clsd_PrepaymentFeePercentageOfOriginalPrincipalAmountOfTermLoans_lbl" xlink:role="http://www.xbrl.org/2003/role/documentation">Prepayment fee percentage of original principal amount of term loans.</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="clsd_PrepaymentFeePercentageOfOriginalPrincipalAmountOfTermLoans_lbl" xlink:role="http://www.xbrl.org/2003/role/label">Prepayment Fee Percentage Of Original Principal Amount Of Term Loans</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="clsd_PrepaymentFeePercentageOfOriginalPrincipalAmountOfTermLoans_lbl" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Transfer of loans held-for-sale to portfolio loans</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_IncreaseDecreaseInOtherOperatingCapitalNet_lbl" xlink:role="http://www.xbrl.org/2003/role/totalLabel">Increase (Decrease) in Other Operating Assets and Liabilities, Net, Total</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_IncreaseDecreaseInOtherOperatingCapitalNet_lbl" xlink:role="http://www.xbrl.org/2003/role/label">Increase (Decrease) in Other Operating Assets and Liabilities, Net</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_IncreaseDecreaseInOtherOperatingCapitalNet_lbl" xlink:role="http://www.xbrl.org/2009/role/negatedLabel">Other assets and liabilities</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="dei_AmendmentFlag_lbl" xlink:role="http://www.xbrl.org/2003/role/label">Amendment Flag</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="dei_AmendmentFlag_lbl" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Amendment Flag</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="clsd_TwoThousandsAndSixteenEquityIncentivePlanMember_lbl" xlink:role="http://www.xbrl.org/2003/role/terseLabel">2016 Equity Incentive Plan</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="clsd_TwoThousandsAndSixteenEquityIncentivePlanMember_lbl" xlink:role="http://www.xbrl.org/2003/role/label">Two Thousands And Sixteen Equity Incentive Plan [Member]</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="clsd_TwoThousandsAndSixteenEquityIncentivePlanMember_lbl" xlink:role="http://www.xbrl.org/2003/role/documentation">Two Thousands And Sixteen Equity Incentive Plan [Member]</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="clsd_ConsiderationForTerritoryExpansionReceived_lbl" xlink:role="http://www.xbrl.org/2003/role/label">Consideration for Territory Expansion Received</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="clsd_ConsiderationForTerritoryExpansionReceived_lbl" xlink:role="http://www.xbrl.org/2003/role/documentation">Consideration for territory expansion received.</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="clsd_UpfrontPayments_lbl" xlink:role="http://www.xbrl.org/2003/role/documentation">Upfront payments.</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="clsd_UpfrontPayments_lbl" xlink:role="http://www.xbrl.org/2003/role/label">Upfront Payments</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="clsd_UpfrontPayments_lbl" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Upfront payment</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_SubsequentEventTypeDomain_lbl" xlink:role="http://www.xbrl.org/2003/role/label">Subsequent Event Type [Domain]</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_ShortTermBorrowings_lbl" xlink:role="http://www.xbrl.org/2003/role/totalLabel">Short-term Debt, Total</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_ShortTermBorrowings_lbl" xlink:role="http://www.xbrl.org/2003/role/label">Short-Term Debt</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_ShortTermBorrowings_lbl" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Short-term Debt</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="clsd_LineOfCreditFacilityRemainingBorrowingCapacityNotAvailableForWithdraw_lbl" xlink:role="http://www.xbrl.org/2003/role/documentation">Line of credit facility remaining borrowing capacity not available for withdraw.</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="clsd_LineOfCreditFacilityRemainingBorrowingCapacityNotAvailableForWithdraw_lbl" xlink:role="http://www.xbrl.org/2003/role/label">Line Of Credit Facility Remaining Borrowing Capacity Not Available For Withdraw</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="clsd_LineOfCreditFacilityRemainingBorrowingCapacityNotAvailableForWithdraw_lbl" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Line of credit facility remaining borrowing capacity not available for withdraw</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_OperatingLeaseRightOfUseAsset_lbl" xlink:role="http://www.xbrl.org/2003/role/label">Operating Lease, Right-of-Use Asset</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_OperatingLeaseRightOfUseAsset_lbl" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Operating lease right-of-use asset</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="dei_DocumentQuarterlyReport_lbl" xlink:role="http://www.xbrl.org/2003/role/label">Document Quarterly Report</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="dei_DocumentQuarterlyReport_lbl" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Document Quarterly Report</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_DebtInstrumentTable_lbl" xlink:role="http://www.xbrl.org/2003/role/label">Schedule of Long-Term Debt Instruments [Table]</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_DebtInstrumentTable_lbl" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Debt Instrument [Table]</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_ScheduleOfNonvestedShareActivityTableTextBlock_lbl" xlink:role="http://www.xbrl.org/2003/role/label">Schedule of Nonvested Share Activity [Table Text Block]</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_ScheduleOfNonvestedShareActivityTableTextBlock_lbl" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Summary of the Activity Related to RSUs</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_ShortTermDebtLineItems_lbl" xlink:role="http://www.xbrl.org/2003/role/label">Short-Term Debt [Line Items]</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_ShortTermDebtLineItems_lbl" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Short Term Debt [Line Items]</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_DebtInstrumentUnusedBorrowingCapacityDescription_lbl" xlink:role="http://www.xbrl.org/2003/role/label">Debt Instrument, Unused Borrowing Capacity, Description</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_DebtInstrumentUnusedBorrowingCapacityDescription_lbl" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Line of credit facility, remaining borrowing capacity description</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_StatementTable_lbl" xlink:role="http://www.xbrl.org/2003/role/label">Statement [Table]</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_StatementTable_lbl" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Statement [Table]</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_OperatingLeaseLiabilityNoncurrent_lbl" xlink:role="http://www.xbrl.org/2003/role/label">Operating Lease, Liability, Noncurrent</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_OperatingLeaseLiabilityNoncurrent_lbl" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Operating lease liabilities</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_OperatingLeasePayments_lbl" xlink:role="http://www.xbrl.org/2003/role/label">Operating Lease, Payments</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_OperatingLeasePayments_lbl" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Cash payments included in operating activities for operating lease liabilities</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="clsd_RoyaltyObligationAbstract_lbl" xlink:role="http://www.xbrl.org/2003/role/label">Royalty Obligation [Abstract]</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="clsd_RoyaltyObligationAbstract_lbl" xlink:role="http://www.xbrl.org/2003/role/documentation">Royalty Obligation</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_StockIssuedDuringPeriodSharesEmployeeStockPurchasePlans_lbl" xlink:role="http://www.xbrl.org/2003/role/verboseLabel">Common stock purchased</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_StockIssuedDuringPeriodSharesEmployeeStockPurchasePlans_lbl" xlink:role="http://www.xbrl.org/2003/role/label">Stock Issued During Period, Shares, Employee Stock Purchase Plans</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_StockIssuedDuringPeriodSharesEmployeeStockPurchasePlans_lbl" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Issuance of common shares under employee stock purchase plan, shares</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_MachineryAndEquipmentMember_lbl" xlink:role="http://www.xbrl.org/2003/role/label">Machinery and Equipment [Member]</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_MachineryAndEquipmentMember_lbl" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Machinery and Equipment</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="clsd_MaximumProceedsFromRoyaltyPurchaseAndSaleAgreement_lbl" xlink:role="http://www.xbrl.org/2003/role/documentation">Maximum proceeds from royalty purchase and sale agreement.</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="clsd_MaximumProceedsFromRoyaltyPurchaseAndSaleAgreement_lbl" xlink:role="http://www.xbrl.org/2003/role/label">Maximum Proceeds from Royalty Purchase and Sale Agreement</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="clsd_MaximumProceedsFromRoyaltyPurchaseAndSaleAgreement_lbl" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Maximum proceeds from royalty purchase and sale agreement</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValue_lbl" xlink:role="http://www.xbrl.org/2003/role/label">Share-Based Compensation Arrangement by Share-Based Payment Award, Equity Instruments Other than Options, Nonvested, Weighted Average Grant Date Fair Value</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValue_lbl" xlink:role="http://www.xbrl.org/2003/role/periodEndLabel">Non-vested units outstanding, Weighted Average Exercise Price, Ending balance</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValue_lbl" xlink:role="http://www.xbrl.org/2003/role/periodStartLabel">Non-vested units outstanding, Weighted Average Exercise Price, Beginning balance</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedInPeriodWeightedAverageGrantDateFairValue_lbl" xlink:role="http://www.xbrl.org/2003/role/label">Share-Based Compensation Arrangement by Share-Based Payment Award, Equity Instruments Other than Options, Vested in Period, Weighted Average Grant Date Fair Value</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedInPeriodWeightedAverageGrantDateFairValue_lbl" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Weighted Average Exercise Price, Vested</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_IncreaseDecreaseInDeferredRevenue_lbl" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Deferred revenue</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_IncreaseDecreaseInDeferredRevenue_lbl" xlink:role="http://www.xbrl.org/2003/role/label">Increase (Decrease) in Deferred Revenue</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="srt_ProductOrServiceAxis_lbl" xlink:role="http://www.xbrl.org/2003/role/label">Product and Service [Axis]</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="srt_ProductOrServiceAxis_lbl" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Product and Service</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_EmployeeRelatedLiabilitiesCurrent_lbl" xlink:role="http://www.xbrl.org/2003/role/totalLabel">Employee-related Liabilities, Current, Total</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_EmployeeRelatedLiabilitiesCurrent_lbl" xlink:role="http://www.xbrl.org/2003/role/label">Employee-related Liabilities, Current</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_EmployeeRelatedLiabilitiesCurrent_lbl" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Accrued employee costs</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="clsd_StockIssuedDuringPeriodValueAtMarketSalesAgreement_lbl" xlink:role="http://www.xbrl.org/2003/role/documentation">Stock issued during period value at market sales agreement.</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="clsd_StockIssuedDuringPeriodValueAtMarketSalesAgreement_lbl" xlink:role="http://www.xbrl.org/2003/role/label">Stock Issued During Period Value At Market Sales Agreement</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="clsd_StockIssuedDuringPeriodValueAtMarketSalesAgreement_lbl" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Issuance of common shares under at-the-market sales agreement</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_EmployeeStockOptionMember_lbl" xlink:role="http://www.xbrl.org/2003/role/label">Share-Based Payment Arrangement, Option [Member]</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_EmployeeStockOptionMember_lbl" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Stock Options</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_EmployeeStockOptionMember_lbl" xlink:role="http://www.xbrl.org/2003/role/verboseLabel">Outstanding Stock Options</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_OperatingLeaseWeightedAverageRemainingLeaseTerm1_lbl" xlink:role="http://www.xbrl.org/2003/role/label">Operating Lease, Weighted Average Remaining Lease Term</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_OperatingLeaseWeightedAverageRemainingLeaseTerm1_lbl" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Operating lease, remaining lease term</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_LiabilitiesAndStockholdersEquity_lbl" xlink:role="http://www.xbrl.org/2003/role/label">Liabilities and Equity</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_LiabilitiesAndStockholdersEquity_lbl" xlink:role="http://www.xbrl.org/2003/role/totalLabel">Total liabilities and stockholders&#8217; equity</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_PlanNameDomain_lbl" xlink:role="http://www.xbrl.org/2003/role/label">Plan Name [Domain]</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_PlanNameDomain_lbl" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Plan Name</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_LineOfCreditFacilityLenderDomain_lbl" xlink:role="http://www.xbrl.org/2003/role/label">Line of Credit Facility, Lender [Domain]</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_LineOfCreditFacilityLenderDomain_lbl" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Line of Credit Facility, Lender</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="clsd_CommercialArrangementMember_lbl" xlink:role="http://www.xbrl.org/2003/role/documentation">Commercial Arrangement.</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="clsd_CommercialArrangementMember_lbl" xlink:role="http://www.xbrl.org/2003/role/label">Commercial Arrangement [Member]</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="clsd_CommercialArrangementMember_lbl" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Commercial Arrangement</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="dei_EntityIncorporationStateCountryCode_lbl" xlink:role="http://www.xbrl.org/2003/role/label">Entity Incorporation, State or Country Code</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="dei_EntityIncorporationStateCountryCode_lbl" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Entity Incorporation, State or Country Code</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_IncomeStatementAbstract_lbl" xlink:role="http://www.xbrl.org/2003/role/label">Income Statement [Abstract]</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_OrganizationConsolidationAndPresentationOfFinancialStatementsDisclosureTextBlock_lbl" xlink:role="http://www.xbrl.org/2003/role/label">Organization, Consolidation and Presentation of Financial Statements Disclosure [Text Block]</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_OrganizationConsolidationAndPresentationOfFinancialStatementsDisclosureTextBlock_lbl" xlink:role="http://www.xbrl.org/2003/role/terseLabel">The Company</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_LiabilitiesCurrent_lbl" xlink:role="http://www.xbrl.org/2003/role/label">Liabilities, Current</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_LiabilitiesCurrent_lbl" xlink:role="http://www.xbrl.org/2003/role/totalLabel">Total current liabilities</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="clsd_NetProceedsAfterDeductingOfferingExpenses_lbl" xlink:role="http://www.xbrl.org/2003/role/verboseLabel">Proceeds from registered direct offering, net of issuance costs</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="clsd_NetProceedsAfterDeductingOfferingExpenses_lbl" xlink:role="http://www.xbrl.org/2009/role/negatedTerseLabel">Proceeds from registered direct offering, net of issuance costs</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="clsd_NetProceedsAfterDeductingOfferingExpenses_lbl" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Net proceeds after deducting offering expenses</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="clsd_NetProceedsAfterDeductingOfferingExpenses_lbl" xlink:role="http://www.xbrl.org/2003/role/label">Net Proceeds After Deducting Offering Expenses</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="clsd_NetProceedsAfterDeductingOfferingExpenses_lbl" xlink:role="http://www.xbrl.org/2003/role/documentation">Net proceeds after deducting offering expenses.</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_StockIssuedDuringPeriodValueEmployeeStockPurchasePlan_lbl" xlink:role="http://www.xbrl.org/2003/role/label">Stock Issued During Period, Value, Employee Stock Purchase Plan</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_StockIssuedDuringPeriodValueEmployeeStockPurchasePlan_lbl" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Issuance of common shares under employee stock purchase plan</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_ShortTermLeaseCost_lbl" xlink:role="http://www.xbrl.org/2003/role/label">Short-Term Lease, Cost</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_ShortTermLeaseCost_lbl" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Short-term Lease, Cost</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_PreferredStockSharesAuthorized_lbl" xlink:role="http://www.xbrl.org/2003/role/label">Preferred Stock, Shares Authorized</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_PreferredStockSharesAuthorized_lbl" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Preferred stock, shares authorized</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="clsd_BaseAnnualRentalIncomeFixedPercentageIncrease_lbl" xlink:role="http://www.xbrl.org/2003/role/documentation">Base annual rental income fixed percentage increase.</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="clsd_BaseAnnualRentalIncomeFixedPercentageIncrease_lbl" xlink:role="http://www.xbrl.org/2003/role/label">Base Annual Rental Income Fixed Percentage Increase</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="clsd_BaseAnnualRentalIncomeFixedPercentageIncrease_lbl" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Percentage of increase per year</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_ScheduleOfEmployeeServiceShareBasedCompensationAllocationOfRecognizedPeriodCostsTable_lbl" xlink:role="http://www.xbrl.org/2003/role/label">Share-Based Payment Arrangement, Expensed and Capitalized, Amount [Table]</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_ScheduleOfEmployeeServiceShareBasedCompensationAllocationOfRecognizedPeriodCostsTable_lbl" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Schedule Of Employee Service Share Based Compensation Allocation Of Recognized Period Costs [Table]</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_TypeOfRevenueExtensibleList_lbl" xlink:role="http://www.xbrl.org/2003/role/label">Revenue, Product and Service [Extensible Enumeration]</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_TypeOfRevenueExtensibleList_lbl" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Type of Revenue [Extensible List]</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="dei_EntitySmallBusiness_lbl" xlink:role="http://www.xbrl.org/2003/role/label">Entity Small Business</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="dei_EntitySmallBusiness_lbl" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Entity Small Business</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_TypeOfArrangementAxis_lbl" xlink:role="http://www.xbrl.org/2003/role/label">Collaborative Arrangement and Arrangement Other than Collaborative [Axis]</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_TypeOfArrangementAxis_lbl" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Collaborative Arrangement and Arrangement Other than Collaborative</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_CompensationRelatedCostsPolicyTextBlock_lbl" xlink:role="http://www.xbrl.org/2003/role/label">Compensation Related Costs, Policy [Policy Text Block]</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_CompensationRelatedCostsPolicyTextBlock_lbl" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Share-Based Compensation</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="clsd_BauschHealthIrelandLimitedMember_lbl" xlink:role="http://www.xbrl.org/2003/role/documentation">Bausch health ireland limited (Bausch).</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="clsd_BauschHealthIrelandLimitedMember_lbl" xlink:role="http://www.xbrl.org/2003/role/label">Bausch Health Ireland Limited [Member]</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="clsd_BauschHealthIrelandLimitedMember_lbl" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Bausch Health Ireland Limited</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="clsd_RoyaltyPurchaseAndSalesAgreementAbstract_lbl" xlink:role="http://www.xbrl.org/2003/role/label">Royalty Purchase and Sales Agreement [Abstract]</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="clsd_RoyaltyPurchaseAndSalesAgreementAbstract_lbl" xlink:role="http://www.xbrl.org/2003/role/documentation">Royalty Purchase and Sales Agreement</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_AssetsCurrent_lbl" xlink:role="http://www.xbrl.org/2003/role/label">Assets, Current</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_AssetsCurrent_lbl" xlink:role="http://www.xbrl.org/2003/role/totalLabel">Total current assets</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_PropertyPlantAndEquipmentLineItems_lbl" xlink:role="http://www.xbrl.org/2003/role/label">Property, Plant and Equipment [Line Items]</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_PropertyPlantAndEquipmentLineItems_lbl" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Property Plant And Equipment [Line Items]</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="clsd_SiliconValleyBankMember_lbl" xlink:role="http://www.xbrl.org/2003/role/documentation">Silicon Valley Bank.</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="clsd_SiliconValleyBankMember_lbl" xlink:role="http://www.xbrl.org/2003/role/label">Silicon Valley Bank [Member]</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="clsd_SiliconValleyBankMember_lbl" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Silicon Valley Bank</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="clsd_RestrictedCashMoneyMarketMember_lbl" xlink:role="http://www.xbrl.org/2003/role/label">Restricted Cash Money Market [Member]</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="clsd_RestrictedCashMoneyMarketMember_lbl" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Restricted Cash Money Market</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="clsd_RestrictedCashMoneyMarketMember_lbl" xlink:role="http://www.xbrl.org/2003/role/documentation">Restricted cash money market.</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_ScheduleOfShortTermDebtTable_lbl" xlink:role="http://www.xbrl.org/2003/role/label">Schedule of Short-Term Debt [Table]</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_ScheduleOfShortTermDebtTable_lbl" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Schedule Of Short Term Debt [Table]</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_WeightedAverageNumberOfSharesOutstandingBasic_lbl" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Weighted average shares outstanding basic</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_WeightedAverageNumberOfSharesOutstandingBasic_lbl" xlink:role="http://www.xbrl.org/2003/role/label">Weighted Average Number of Shares Outstanding, Basic</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_WeightedAverageNumberOfSharesOutstandingBasic_lbl" xlink:role="http://www.xbrl.org/2003/role/totalLabel">Weighted Average Number of Shares Outstanding, Basic, Total</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_DebtRelatedCommitmentFeesAndDebtIssuanceCosts_lbl" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Royalty purchased</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_DebtRelatedCommitmentFeesAndDebtIssuanceCosts_lbl" xlink:role="http://www.xbrl.org/2003/role/verboseLabel">Issuance costs</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_DebtRelatedCommitmentFeesAndDebtIssuanceCosts_lbl" xlink:role="http://www.xbrl.org/2003/role/label">Debt Related Commitment Fees and Debt Issuance Costs</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="dei_CityAreaCode_lbl" xlink:role="http://www.xbrl.org/2003/role/label">City Area Code</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="dei_CityAreaCode_lbl" xlink:role="http://www.xbrl.org/2003/role/terseLabel">City Area Code</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="clsd_ReconciliationOfCashCashEquivalentsAndRestrictedCashAbstract_lbl" xlink:role="http://www.xbrl.org/2003/role/documentation">Reconciliation of cash, cash equivalents and restricted cash.</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="clsd_ReconciliationOfCashCashEquivalentsAndRestrictedCashAbstract_lbl" xlink:role="http://www.xbrl.org/2003/role/label">Reconciliation Of Cash Cash Equivalents And Restricted Cash [Abstract]</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="clsd_ReconciliationOfCashCashEquivalentsAndRestrictedCashAbstract_lbl" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Reconciliation of cash, cash equivalents and restricted cash</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsForfeituresInPeriod_lbl" xlink:role="http://www.xbrl.org/2003/role/label">Share-Based Compensation Arrangement by Share-Based Payment Award, Options, Forfeitures in Period</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsForfeituresInPeriod_lbl" xlink:role="http://www.xbrl.org/2009/role/negatedLabel">Number of Shares, Forfeited</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_DisclosureOfCompensationRelatedCostsSharebasedPaymentsAbstract_lbl" xlink:role="http://www.xbrl.org/2003/role/label">Share-Based Payment Arrangement [Abstract]</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_Liabilities_lbl" xlink:role="http://www.xbrl.org/2003/role/label">Liabilities</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_Liabilities_lbl" xlink:role="http://www.xbrl.org/2003/role/totalLabel">Total liabilities</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="dei_DocumentPeriodEndDate_lbl" xlink:role="http://www.xbrl.org/2003/role/label">Document Period End Date</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="dei_DocumentPeriodEndDate_lbl" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Document Period End Date</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_PaymentsOfStockIssuanceCosts_lbl" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Issuance costs</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_PaymentsOfStockIssuanceCosts_lbl" xlink:role="http://www.xbrl.org/2003/role/label">Payments of Stock Issuance Costs</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_ConstructionInProgressMember_lbl" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Construction-in-process</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_ConstructionInProgressMember_lbl" xlink:role="http://www.xbrl.org/2003/role/label">Construction in Progress [Member]</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_LesseeOperatingLeaseRenewalTerm_lbl" xlink:role="http://www.xbrl.org/2003/role/label">Lessee, Operating Lease, Renewal Term</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_LesseeOperatingLeaseRenewalTerm_lbl" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Operating lease agreement renewal option term</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="srt_RangeAxis_lbl" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Statistical Measurement</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="srt_RangeAxis_lbl" xlink:role="http://www.xbrl.org/2003/role/label">Statistical Measurement [Axis]</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="clsd_EligiblePayrollCosts_lbl" xlink:role="http://www.xbrl.org/2003/role/documentation">Eligible payroll costs.</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="clsd_EligiblePayrollCosts_lbl" xlink:role="http://www.xbrl.org/2003/role/label">Eligible Payroll Costs</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="clsd_EligiblePayrollCosts_lbl" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Eligible Payroll Costs</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_OtherAssetsCurrent_lbl" xlink:role="http://www.xbrl.org/2003/role/label">Other Assets, Current</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_OtherAssetsCurrent_lbl" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Other current assets</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_Assets_lbl" xlink:role="http://www.xbrl.org/2003/role/label">Assets</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_Assets_lbl" xlink:role="http://www.xbrl.org/2003/role/totalLabel">Total assets</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_EarningsPerShareDiluted_lbl" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Net loss per share of common stock diluted</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_EarningsPerShareDiluted_lbl" xlink:role="http://www.xbrl.org/2003/role/label">Earnings Per Share, Diluted</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_EarningsPerShareDiluted_lbl" xlink:role="http://www.xbrl.org/2003/role/totalLabel">Earnings Per Share, Diluted, Total</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="clsd_StockPurchaseWarrantsDisclosureTextBlock_lbl" xlink:role="http://www.xbrl.org/2003/role/documentation">Stock purchase warrants disclosure.</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="clsd_StockPurchaseWarrantsDisclosureTextBlock_lbl" xlink:role="http://www.xbrl.org/2003/role/label">Stock Purchase Warrants Disclosure [Text Block]</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="clsd_StockPurchaseWarrantsDisclosureTextBlock_lbl" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Stock Purchase Warrants</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="clsd_CommitmentAndContingenciesLineItems_lbl" xlink:role="http://www.xbrl.org/2003/role/documentation">Commitment and Contingencies [Line Items].</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="clsd_CommitmentAndContingenciesLineItems_lbl" xlink:role="http://www.xbrl.org/2003/role/label">Commitment And Contingencies [Line Items]</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="clsd_CommitmentAndContingenciesLineItems_lbl" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Commitment And Contingencies [Line Items]</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_ScheduleOfAntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareTextBlock_lbl" xlink:role="http://www.xbrl.org/2003/role/label">Schedule of Antidilutive Securities Excluded from Computation of Earnings Per Share [Table Text Block]</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_ScheduleOfAntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareTextBlock_lbl" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Potential Common Stock Equivalents Excluded from Computation of Diluted Net Loss per Share</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="dei_EntityAddressPostalZipCode_lbl" xlink:role="http://www.xbrl.org/2003/role/label">Entity Address, Postal Zip Code</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="dei_EntityAddressPostalZipCode_lbl" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Entity Address, Postal Zip Code</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="clsd_CommonStockWarrantsMember_lbl" xlink:role="http://www.xbrl.org/2003/role/documentation">Common stock warrants.</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="clsd_CommonStockWarrantsMember_lbl" xlink:role="http://www.xbrl.org/2003/role/label">Common Stock Warrants [Member]</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="clsd_CommonStockWarrantsMember_lbl" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Convertible Stock Warrant</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="clsd_ForgivenessOfPaycheckProtectionProgramLoanAndAccruedInterest_lbl" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Forgiveness of PPP Loan and accrued interest</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="clsd_ForgivenessOfPaycheckProtectionProgramLoanAndAccruedInterest_lbl" xlink:role="http://www.xbrl.org/2003/role/label">Forgiveness Of Paycheck Protection Program Loan And Accrued Interest</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="clsd_ForgivenessOfPaycheckProtectionProgramLoanAndAccruedInterest_lbl" xlink:role="http://www.xbrl.org/2003/role/documentation">Forgiveness of Paycheck Protection Program loan and accrued interest.</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="dei_DocumentFiscalPeriodFocus_lbl" xlink:role="http://www.xbrl.org/2003/role/label">Document Fiscal Period Focus</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="dei_DocumentFiscalPeriodFocus_lbl" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Document Fiscal Period Focus</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_RestrictedCash_lbl" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Restricted cash (including $100 for each period recorded in other current assets)</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_RestrictedCash_lbl" xlink:role="http://www.xbrl.org/2003/role/totalLabel">Restricted Cash, Total</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_RestrictedCash_lbl" xlink:role="http://www.xbrl.org/2003/role/label">Restricted Cash</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_RestrictedCash_lbl" xlink:role="http://www.xbrl.org/2003/role/periodEndLabel">Restricted cash</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_ClassOfWarrantOrRightTable_lbl" xlink:role="http://www.xbrl.org/2003/role/label">Class of Warrant or Right [Table]</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_ClassOfWarrantOrRightTable_lbl" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Class Of Warrant Or Right [Table]</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="clsd_IssuanceOfCommonSharesValueUnderADirectRegisteredOffering_lbl" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Issuance of common shares under a direct registered offering</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="clsd_IssuanceOfCommonSharesValueUnderADirectRegisteredOffering_lbl" xlink:role="http://www.xbrl.org/2003/role/label">Issuance of common shares value under a direct registered offering</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="clsd_IssuanceOfCommonSharesValueUnderADirectRegisteredOffering_lbl" xlink:role="http://www.xbrl.org/2003/role/documentation">Issuance of common shares value under a direct registered offering</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_PreferredStockValue_lbl" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Preferred stock, $0.001 par value; 10,000,000 shares authorized and no shares issued at September 30, 2022 and December 31, 2021</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_PreferredStockValue_lbl" xlink:role="http://www.xbrl.org/2003/role/periodEndLabel">Preferred Stock, Value, Issued, Ending Balance</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_PreferredStockValue_lbl" xlink:role="http://www.xbrl.org/2003/role/periodStartLabel">Preferred Stock, Value, Issued, Beginning Balance</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_PreferredStockValue_lbl" xlink:role="http://www.xbrl.org/2003/role/totalLabel">Preferred Stock, Value, Issued, Total</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_PreferredStockValue_lbl" xlink:role="http://www.xbrl.org/2003/role/label">Preferred Stock, Value, Issued</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_AdjustmentsToAdditionalPaidInCapitalSharebasedCompensationRequisiteServicePeriodRecognitionValue_lbl" xlink:role="http://www.xbrl.org/2003/role/totalLabel">APIC, Share-based Payment Arrangement, Increase for Cost Recognition, Total</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_AdjustmentsToAdditionalPaidInCapitalSharebasedCompensationRequisiteServicePeriodRecognitionValue_lbl" xlink:role="http://www.xbrl.org/2003/role/label">APIC, Share-Based Payment Arrangement, Increase for Cost Recognition</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_AdjustmentsToAdditionalPaidInCapitalSharebasedCompensationRequisiteServicePeriodRecognitionValue_lbl" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Share-based compensation expense</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="clsd_AdditionalMilestonePayment_lbl" xlink:role="http://www.xbrl.org/2003/role/label">Additional Milestone Payment</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="clsd_AdditionalMilestonePayment_lbl" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Additional milestone payments</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="clsd_AdditionalMilestonePayment_lbl" xlink:role="http://www.xbrl.org/2003/role/documentation">Additional milestone payment.</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="srt_RepurchaseAgreementCounterpartyNameDomain_lbl" xlink:role="http://www.xbrl.org/2003/role/label">Counterparty Name [Domain]</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_OtherNonoperatingIncome_lbl" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Other income</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_OtherNonoperatingIncome_lbl" xlink:role="http://www.xbrl.org/2003/role/label">Other Nonoperating Income</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_OperatingLeaseLiability_lbl" xlink:role="http://www.xbrl.org/2003/role/verboseLabel">Total operating lease liabilities</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_OperatingLeaseLiability_lbl" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Operating lease liabilities</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_OperatingLeaseLiability_lbl" xlink:role="http://www.xbrl.org/2003/role/label">Operating Lease, Liability</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_OperatingLeaseLiability_lbl" xlink:role="http://www.xbrl.org/2003/role/totalLabel">Total operating lease liabilities</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="clsd_XipereMember_lbl" xlink:role="http://www.xbrl.org/2003/role/label">XIPERE [Member]</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="clsd_XipereMember_lbl" xlink:role="http://www.xbrl.org/2003/role/documentation">XIPERE member</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_NetCashProvidedByUsedInFinancingActivities_lbl" xlink:role="http://www.xbrl.org/2003/role/totalLabel">Net cash provided by financing activities</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_NetCashProvidedByUsedInFinancingActivities_lbl" xlink:role="http://www.xbrl.org/2003/role/label">Net Cash Provided by (Used in) Financing Activities</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="clsd_ScheduleOfActivityOfPurchaseAndSaleAgreementTableTextBlock_lbl" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Schedule of activity of the royalty obligation</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="clsd_ScheduleOfActivityOfPurchaseAndSaleAgreementTableTextBlock_lbl" xlink:role="http://www.xbrl.org/2003/role/label">Schedule of Activity of Purchase and Sale Agreement [Table Text Block]</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="clsd_ScheduleOfActivityOfPurchaseAndSaleAgreementTableTextBlock_lbl" xlink:role="http://www.xbrl.org/2003/role/documentation">Schedule of activity of purchase and sale agreement.</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_InterestExpenseBorrowings_lbl" xlink:role="http://www.xbrl.org/2003/role/totalLabel">Interest Expense, Borrowings, Total</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_InterestExpenseBorrowings_lbl" xlink:role="http://www.xbrl.org/2003/role/label">Interest Expense, Borrowings</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_InterestExpenseBorrowings_lbl" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Interest expense on borrowings</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_OperatingLeasesFutureMinimumPaymentsDue_lbl" xlink:role="http://www.xbrl.org/2003/role/label">Operating Leases, Future Minimum Payments Due</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_OperatingLeasesFutureMinimumPaymentsDue_lbl" xlink:role="http://www.xbrl.org/2003/role/totalLabel">Operating Leases, Future Minimum Payments Due, Total</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_StatementOfFinancialPositionAbstract_lbl" xlink:role="http://www.xbrl.org/2003/role/label">Statement of Financial Position [Abstract]</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="dei_EntityFileNumber_lbl" xlink:role="http://www.xbrl.org/2003/role/label">Securities Act File Number</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="dei_EntityFileNumber_lbl" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Entity File Number</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="srt_ScenarioUnspecifiedDomain_lbl" xlink:role="http://www.xbrl.org/2003/role/label">Scenario [Domain]</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_DebtorInPossessionFinancingInterestRateOnBorrowingsOutstanding_lbl" xlink:role="http://www.xbrl.org/2003/role/label">Debtor-in-Possession Financing, Interest Rate on Borrowings Outstanding</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_DebtorInPossessionFinancingInterestRateOnBorrowingsOutstanding_lbl" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Interest rate on outstanding principal amount</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_StatementOfCashFlowsAbstract_lbl" xlink:role="http://www.xbrl.org/2003/role/label">Statement of Cash Flows [Abstract]</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_ClassOfWarrantOrRightNumberOfSecuritiesCalledByEachWarrantOrRight_lbl" xlink:role="http://www.xbrl.org/2003/role/label">Class of Warrant or Right, Number of Securities Called by Each Warrant or Right</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_ClassOfWarrantOrRightNumberOfSecuritiesCalledByEachWarrantOrRight_lbl" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Number of stock that can be purchased by each warrant</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_DeferredRevenueArrangementTypeAxis_lbl" xlink:role="http://www.xbrl.org/2003/role/label">Deferred Revenue Arrangement Type [Axis]</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_DeferredRevenueArrangementTypeAxis_lbl" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Deferred Revenue Arrangement Type</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="clsd_CashAndMoneyMarketsMember_lbl" xlink:role="http://www.xbrl.org/2003/role/documentation">Cash and money markets.</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="clsd_CashAndMoneyMarketsMember_lbl" xlink:role="http://www.xbrl.org/2003/role/label">Cash And Money Markets [Member]</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="clsd_CashAndMoneyMarketsMember_lbl" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Cash and Money Markets</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_ClassOfWarrantOrRightLineItems_lbl" xlink:role="http://www.xbrl.org/2003/role/label">Class of Warrant or Right [Line Items]</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_ClassOfWarrantOrRightLineItems_lbl" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Class Of Warrant Or Right [Line Items]</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="srt_SegmentGeographicalDomain_lbl" xlink:role="http://www.xbrl.org/2003/role/label">Geographical [Domain]</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="srt_SegmentGeographicalDomain_lbl" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Geographical</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="srt_RangeMember_lbl" xlink:role="http://www.xbrl.org/2003/role/label">Statistical Measurement [Domain]</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="srt_RangeMember_lbl" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Statistical Measurement</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_StatementOfStockholdersEquityAbstract_lbl" xlink:role="http://www.xbrl.org/2003/role/label">Statement of Stockholders' Equity [Abstract]</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_RevenueFromContractWithCustomerPolicyTextBlock_lbl" xlink:role="http://www.xbrl.org/2003/role/label">Revenue from Contract with Customer [Policy Text Block]</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_RevenueFromContractWithCustomerPolicyTextBlock_lbl" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Revenue Recognition</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_SubsequentEventsAbstract_lbl" xlink:role="http://www.xbrl.org/2003/role/label">Subsequent Events [Abstract]</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_FairValueDisclosuresTextBlock_lbl" xlink:role="http://www.xbrl.org/2003/role/label">Fair Value Disclosures [Text Block]</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_FairValueDisclosuresTextBlock_lbl" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Fair Value Measurements</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_ProceedsFromStockOptionsExercised_lbl" xlink:role="http://www.xbrl.org/2003/role/label">Proceeds from Stock Options Exercised</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_ProceedsFromStockOptionsExercised_lbl" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Proceeds from exercise of stock options</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="clsd_PaycheckProtectionProgramMember_lbl" xlink:role="http://www.xbrl.org/2003/role/documentation">Paycheck protection program.</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="clsd_PaycheckProtectionProgramMember_lbl" xlink:role="http://www.xbrl.org/2003/role/label">Paycheck Protection Program [Member]</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="clsd_PaycheckProtectionProgramMember_lbl" xlink:role="http://www.xbrl.org/2003/role/terseLabel">PPP Loan</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="clsd_MilestonePayments_lbl" xlink:role="http://www.xbrl.org/2003/role/documentation">Milestone payments.</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="clsd_MilestonePayments_lbl" xlink:role="http://www.xbrl.org/2003/role/label">Milestone Payments</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_PropertyPlantAndEquipmentTextBlock_lbl" xlink:role="http://www.xbrl.org/2003/role/label">Property, Plant and Equipment [Table Text Block]</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_PropertyPlantAndEquipmentTextBlock_lbl" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Schedule of Property and Equipment, Net</link:label>
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    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="clsd_RegenxbioIncMember_lbl" xlink:role="http://www.xbrl.org/2003/role/label">REGENXBIO, Inc.[Member]</link:label>
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    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_ConcentrationRiskCreditRisk_lbl" xlink:role="http://www.xbrl.org/2003/role/label">Concentration Risk, Credit Risk, Policy [Policy Text Block]</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_ConcentrationRiskCreditRisk_lbl" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Concentration of Credit Risk Arising From Cash Deposits in Excess of Insured Limits</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="clsd_LiabilityRelatedToSalesOfFutureRoyaltiesAndNonCashInterestExpensePolicyTextBlock_lbl" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Liability Related to the Sales of Future Royalties and Non-Cash Interest Expense</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="clsd_LiabilityRelatedToSalesOfFutureRoyaltiesAndNonCashInterestExpensePolicyTextBlock_lbl" xlink:role="http://www.xbrl.org/2003/role/label">Liability Related to Sales of Future Royalties and Non Cash Interest Expense [Policy Text Block]</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="clsd_LiabilityRelatedToSalesOfFutureRoyaltiesAndNonCashInterestExpensePolicyTextBlock_lbl" xlink:role="http://www.xbrl.org/2003/role/documentation">Liability related to sales of future royalties and non cash interest expense.</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareByAntidilutiveSecuritiesAxis_lbl" xlink:role="http://www.xbrl.org/2003/role/label">Antidilutive Securities [Axis]</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareByAntidilutiveSecuritiesAxis_lbl" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Antidilutive Securities</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_LineOfCreditFacilityMaximumBorrowingCapacity_lbl" xlink:role="http://www.xbrl.org/2003/role/label">Line of Credit Facility, Maximum Borrowing Capacity</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_LineOfCreditFacilityMaximumBorrowingCapacity_lbl" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Line of credit facility, maximum borrowing capacity</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_PreferredStockParOrStatedValuePerShare_lbl" xlink:role="http://www.xbrl.org/2003/role/label">Preferred Stock, Par or Stated Value Per Share</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_PreferredStockParOrStatedValuePerShare_lbl" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Preferred stock, par value</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="clsd_LicenseAndOtherAgreementAbstract_lbl" xlink:role="http://www.xbrl.org/2003/role/documentation">License and other agreement.</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="clsd_LicenseAndOtherAgreementAbstract_lbl" xlink:role="http://www.xbrl.org/2003/role/label">License And Other Agreement [Abstract]</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_CreditFacilityDomain_lbl" xlink:role="http://www.xbrl.org/2003/role/label">Credit Facility [Domain]</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_CreditFacilityDomain_lbl" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Credit Facility</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_SubsequentEventsTextBlock_lbl" xlink:role="http://www.xbrl.org/2003/role/label">Subsequent Events [Text Block]</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_SubsequentEventsTextBlock_lbl" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Subsequent Event</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_CollaborativeArrangementsAndNoncollaborativeArrangementTransactionsLineItems_lbl" xlink:role="http://www.xbrl.org/2003/role/label">Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_WeightedAverageNumberOfDilutedSharesOutstanding_lbl" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Weighted average shares outstanding diluted</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_WeightedAverageNumberOfDilutedSharesOutstanding_lbl" xlink:role="http://www.xbrl.org/2003/role/label">Weighted Average Number of Shares Outstanding, Diluted</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_WeightedAverageNumberOfDilutedSharesOutstanding_lbl" xlink:role="http://www.xbrl.org/2003/role/totalLabel">Weighted Average Number of Shares Outstanding, Diluted, Total</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain_lbl" xlink:role="http://www.xbrl.org/2003/role/label">Finite-Lived Intangible Assets, Major Class Name [Domain]</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_CreditFacilityAxis_lbl" xlink:role="http://www.xbrl.org/2003/role/label">Credit Facility [Axis]</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_CreditFacilityAxis_lbl" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Credit Facility</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_EmployeeServiceShareBasedCompensationNonvestedAwardsTotalCompensationCostNotYetRecognizedShareBasedAwardsOtherThanOptions_lbl" xlink:role="http://www.xbrl.org/2003/role/label">Share-Based Payment Arrangement, Nonvested Award, Excluding Option, Cost Not yet Recognized, Amount</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_EmployeeServiceShareBasedCompensationNonvestedAwardsTotalCompensationCostNotYetRecognizedShareBasedAwardsOtherThanOptions_lbl" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Unrecognized compensation expense related to the RSUs</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="clsd_TwoThousandsAndElevenStockIncentivePlanTwoThousandsAndSixteenEquityIncentivePlanMember_lbl" xlink:role="http://www.xbrl.org/2003/role/documentation">Two thousands and eleven stock incentive plan two thousands and sixteen equity incentive plan.</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="clsd_TwoThousandsAndElevenStockIncentivePlanTwoThousandsAndSixteenEquityIncentivePlanMember_lbl" xlink:role="http://www.xbrl.org/2003/role/label">Two Thousands And Eleven Stock Incentive Plan Two Thousands And Sixteen Equity Incentive Plan [Member]</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="clsd_TwoThousandsAndElevenStockIncentivePlanTwoThousandsAndSixteenEquityIncentivePlanMember_lbl" xlink:role="http://www.xbrl.org/2003/role/terseLabel">2011 Stock Incentive Plan, 2016 Equity Incentive Plan</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_ComputerEquipmentMember_lbl" xlink:role="http://www.xbrl.org/2003/role/label">Computer Equipment [Member]</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_ComputerEquipmentMember_lbl" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Computer Equipment</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_GeneralAndAdministrativeExpenseMember_lbl" xlink:role="http://www.xbrl.org/2003/role/label">General and Administrative Expense [Member]</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_GeneralAndAdministrativeExpenseMember_lbl" xlink:role="http://www.xbrl.org/2003/role/terseLabel">General and Administrative</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_ResearchAndDevelopmentArrangementContractToPerformForOthersTypeDomain_lbl" xlink:role="http://www.xbrl.org/2003/role/label">Research and Development Arrangement, Contract to Perform for Others, Type [Domain]</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_ResearchAndDevelopmentArrangementContractToPerformForOthersTypeDomain_lbl" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Research and Development Arrangement, Contract to Perform for Others, Type</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_EmployeeServiceShareBasedCompensationNonvestedAwardsTotalCompensationCostNotYetRecognizedStockOptions_lbl" xlink:role="http://www.xbrl.org/2003/role/label">Share-Based Payment Arrangement, Nonvested Award, Option, Cost Not yet Recognized, Amount</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_EmployeeServiceShareBasedCompensationNonvestedAwardsTotalCompensationCostNotYetRecognizedStockOptions_lbl" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Unrecognized compensation expense related to unvested stock options</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="clsd_SecondAmendedAndRestatedLoanAndSecurityAgreementFirstTrancheMember_lbl" xlink:role="http://www.xbrl.org/2003/role/documentation">Second amended and restated loan and security agreement, first tranche.</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="clsd_SecondAmendedAndRestatedLoanAndSecurityAgreementFirstTrancheMember_lbl" xlink:role="http://www.xbrl.org/2003/role/label">Second Amended And Restated Loan And Security Agreement First Tranche [Member]</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="clsd_SecondAmendedAndRestatedLoanAndSecurityAgreementFirstTrancheMember_lbl" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Second Amended and Restated Loan and Security Agreement, Initial Tranche</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="dei_CurrentFiscalYearEndDate_lbl" xlink:role="http://www.xbrl.org/2003/role/label">Current Fiscal Year End Date</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="dei_CurrentFiscalYearEndDate_lbl" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Current Fiscal Year End Date</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_Depreciation_lbl" xlink:role="http://www.xbrl.org/2003/role/totalLabel">Depreciation, Total</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_Depreciation_lbl" xlink:role="http://www.xbrl.org/2003/role/label">Depreciation</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_Depreciation_lbl" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Depreciation</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalentsIncludingDisposalGroupAndDiscontinuedOperations_lbl" xlink:role="http://www.xbrl.org/2003/role/totalLabel">Cash, cash equivalents and restricted cash at end of period</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalentsIncludingDisposalGroupAndDiscontinuedOperations_lbl" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Cash, cash equivalents and restricted cash, end of period</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalentsIncludingDisposalGroupAndDiscontinuedOperations_lbl" xlink:role="http://www.xbrl.org/2003/role/label">Cash, Cash Equivalents, Restricted Cash, and Restricted Cash Equivalents, Including Disposal Group and Discontinued Operations</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalentsIncludingDisposalGroupAndDiscontinuedOperations_lbl" xlink:role="http://www.xbrl.org/2003/role/periodEndLabel">Cash, cash equivalents and restricted cash, end of period</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalentsIncludingDisposalGroupAndDiscontinuedOperations_lbl" xlink:role="http://www.xbrl.org/2003/role/periodStartLabel">Cash, cash equivalents and restricted cash, beginning of period</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="dei_EntityAddressAddressLine1_lbl" xlink:role="http://www.xbrl.org/2003/role/label">Entity Address, Address Line One</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="dei_EntityAddressAddressLine1_lbl" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Entity Address, Address Line One</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis_lbl" xlink:role="http://www.xbrl.org/2003/role/label">Finite-Lived Intangible Assets by Major Class [Axis]</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="clsd_OtherAgreementMember_lbl" xlink:role="http://www.xbrl.org/2003/role/documentation">Other agreement.</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="clsd_OtherAgreementMember_lbl" xlink:role="http://www.xbrl.org/2003/role/label">Other Agreement [Member]</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="clsd_OtherAgreementMember_lbl" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Other Agreement</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="clsd_NonCashInterestExpenseOnLiabilityRelatedToSalesOfFutureRoyalties_lbl" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Non-cash interest expense on liability related to the sales of future royalties</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="clsd_NonCashInterestExpenseOnLiabilityRelatedToSalesOfFutureRoyalties_lbl" xlink:role="http://www.xbrl.org/2003/role/label">Non Cash Interest Expense on Liability Related to Sales of Future Royalties</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="clsd_NonCashInterestExpenseOnLiabilityRelatedToSalesOfFutureRoyalties_lbl" xlink:role="http://www.xbrl.org/2003/role/documentation">Non cash interest expense on liability related to sales of future royalties.</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_ExtraordinaryAndUnusualItemsAbstract_lbl" xlink:role="http://www.xbrl.org/2003/role/label">Unusual or Infrequent Items, or Both [Abstract]</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_PreferredStockSharesIssued_lbl" xlink:role="http://www.xbrl.org/2003/role/totalLabel">Preferred Stock, Shares Issued, Total</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_PreferredStockSharesIssued_lbl" xlink:role="http://www.xbrl.org/2003/role/label">Preferred Stock, Shares Issued</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_PreferredStockSharesIssued_lbl" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Preferred stock, shares issued</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_OtherAccruedLiabilitiesCurrent_lbl" xlink:role="http://www.xbrl.org/2003/role/label">Other Accrued Liabilities, Current</link:label>
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    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_PaymentsToAcquirePropertyPlantAndEquipment_lbl" xlink:role="http://www.xbrl.org/2009/role/negatedLabel">Acquisition of property and equipment</link:label>
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    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="clsd_RoyaltyPurchaseAndSaleAgreementIssuanceCosts_lbl" xlink:role="http://www.xbrl.org/2003/role/label">Royalty Purchase And Sale Agreement Issuance Costs</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="clsd_RoyaltyPurchaseAndSaleAgreementIssuanceCosts_lbl" xlink:role="http://www.xbrl.org/2003/role/documentation">Royalty Purchase And Sale Agreement Issuance Costs</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_AssetsFairValueDisclosureAbstract_lbl" xlink:role="http://www.xbrl.org/2003/role/label">Assets, Fair Value Disclosure [Abstract]</link:label>
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    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_StockIssuedDuringPeriodValueRestrictedStockAwardNetOfForfeitures_lbl" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Vesting and settlement of restricted stock units</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_StockIssuedDuringPeriodValueRestrictedStockAwardNetOfForfeitures_lbl" xlink:role="http://www.xbrl.org/2003/role/totalLabel">Stock Issued During Period, Value, Restricted Stock Award, Net of Forfeitures, Total</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_StockIssuedDuringPeriodValueRestrictedStockAwardNetOfForfeitures_lbl" xlink:role="http://www.xbrl.org/2003/role/label">Stock Issued During Period, Value, Restricted Stock Award, Net of Forfeitures</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_FairValueByFairValueHierarchyLevelAxis_lbl" xlink:role="http://www.xbrl.org/2003/role/label">Fair Value Hierarchy and NAV [Axis]</link:label>
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    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="clsd_FinalPaymentMember_lbl" xlink:role="http://www.xbrl.org/2003/role/documentation">Final payment.</link:label>
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    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="clsd_FinalPaymentMember_lbl" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Final Payment</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_ScheduleOfResearchAndDevelopmentArrangementContractToPerformForOthersTable_lbl" xlink:role="http://www.xbrl.org/2003/role/label">Schedule of Research and Development Arrangement, Contract to Perform for Others [Table]</link:label>
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    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_EquityAbstract_lbl" xlink:role="http://www.xbrl.org/2003/role/label">Equity [Abstract]</link:label>
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    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_DebtInstrumentInterestRateStatedPercentage_lbl" xlink:role="http://www.xbrl.org/2003/role/label">Debt Instrument, Interest Rate, Stated Percentage</link:label>
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    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_LesseeOperatingLeaseOptionToExtend_lbl" xlink:role="http://www.xbrl.org/2003/role/label">Lessee, Operating Lease, Option to Extend</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_LesseeOperatingLeaseOptionToExtend_lbl" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Lessee, operating lease, option to extend, description</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="clsd_PurchaseAndSaleAgreementDescription_lbl" xlink:role="http://www.xbrl.org/2003/role/documentation">Purchase and Sale Agreement Description</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="clsd_PurchaseAndSaleAgreementDescription_lbl" xlink:role="http://www.xbrl.org/2003/role/label">Purchase and Sale Agreement Description</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="clsd_PurchaseAndSaleAgreementDescription_lbl" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Purchase and sale agreement description</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="srt_StatementScenarioAxis_lbl" xlink:role="http://www.xbrl.org/2003/role/label">Scenario [Axis]</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_ScheduleOfCollaborativeArrangementsAndNoncollaborativeArrangementTransactionsTable_lbl" xlink:role="http://www.xbrl.org/2003/role/label">Collaborative Arrangement and Arrangement Other than Collaborative [Table]</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_ScheduleOfActivityInAffordableHousingProgramObligationTableTextBlock_lbl" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Schedule of activity of the royalty obligation</link:label>
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    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_AccruedProfessionalFeesCurrent_lbl" xlink:role="http://www.xbrl.org/2003/role/label">Accrued Professional Fees, Current</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_AccruedProfessionalFeesCurrent_lbl" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Accrued professional fees</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="dei_EntityFilerCategory_lbl" xlink:role="http://www.xbrl.org/2003/role/label">Entity Filer Category</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="dei_EntityFilerCategory_lbl" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Entity Filer Category</link:label>
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    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="clsd_RoyaltySubMember_lbl" xlink:role="http://www.xbrl.org/2003/role/label">Royalty Sub [Member]</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="clsd_RoyaltySubMember_lbl" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Royalty Sub</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_OperatingExpenses_lbl" xlink:role="http://www.xbrl.org/2009/role/negatedTotalLabel">Total operating expenses</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_OperatingExpenses_lbl" xlink:role="http://www.xbrl.org/2003/role/label">Operating Expenses</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_OperatingExpenses_lbl" xlink:role="http://www.xbrl.org/2003/role/totalLabel">Total operating expenses</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="dei_EntityCurrentReportingStatus_lbl" xlink:role="http://www.xbrl.org/2003/role/label">Entity Current Reporting Status</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="dei_EntityCurrentReportingStatus_lbl" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Entity Current Reporting Status</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_FairValueAssetsMeasuredOnRecurringBasisUnobservableInputReconciliationByAssetClassDomain_lbl" xlink:role="http://www.xbrl.org/2003/role/label">Asset Class [Domain]</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_FairValueAssetsMeasuredOnRecurringBasisUnobservableInputReconciliationByAssetClassDomain_lbl" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Asset Class</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_InventoryNet_lbl" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Inventory</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_InventoryNet_lbl" xlink:role="http://www.xbrl.org/2003/role/label">Inventory, Net</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_InventoryNet_lbl" xlink:role="http://www.xbrl.org/2003/role/totalLabel">Inventory, Net, Total</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="clsd_RoyaltyPurchaseAndSaleAgreementMember_lbl" xlink:role="http://www.xbrl.org/2003/role/documentation">Royalty Purchase and Sale Agreement</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="clsd_RoyaltyPurchaseAndSaleAgreementMember_lbl" xlink:role="http://www.xbrl.org/2003/role/label">Royalty Purchase and Sale Agreement [Member]</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="clsd_RoyaltyPurchaseAndSaleAgreementMember_lbl" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Royalty Purchase and Sale Agreement</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="clsd_AccretionOfFinalPaymentOfAmountBorrowed_lbl" xlink:role="http://www.xbrl.org/2003/role/documentation">Accretion of final payment of amount borrowed.</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="clsd_AccretionOfFinalPaymentOfAmountBorrowed_lbl" xlink:role="http://www.xbrl.org/2003/role/label">Accretion Of Final Payment Of Amount Borrowed</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="clsd_AccretionOfFinalPaymentOfAmountBorrowed_lbl" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Accretion of scheduled final payment</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_RevenueRecognitionMilestoneMethodRevenueRecognized_lbl" xlink:role="http://www.xbrl.org/2003/role/label">Revenue Recognition, Milestone Method, Revenue Recognized</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_RevenueRecognitionMilestoneMethodRevenueRecognized_lbl" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Additional amount</link:label>
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    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_StockholdersEquityNoteDisclosureTextBlock_lbl" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Common Stock</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="clsd_IncrementalBorrowingRate_lbl" xlink:role="http://www.xbrl.org/2003/role/documentation">Incremental borrowing rate.</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="clsd_IncrementalBorrowingRate_lbl" xlink:role="http://www.xbrl.org/2003/role/label">Incremental Borrowing Rate</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="clsd_IncrementalBorrowingRate_lbl" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Incremental borrowing rate</link:label>
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    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_StockholdersEquity_lbl" xlink:role="http://www.xbrl.org/2003/role/periodEndLabel">Ending balance</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_StockholdersEquity_lbl" xlink:role="http://www.xbrl.org/2003/role/periodStartLabel">Beginning balance</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_StockholdersEquity_lbl" xlink:role="http://www.xbrl.org/2003/role/totalLabel">Total stockholders&#8217; equity</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_FairValueByAssetClassAxis_lbl" xlink:role="http://www.xbrl.org/2003/role/label">Asset Class [Axis]</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_FairValueByAssetClassAxis_lbl" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Asset Class</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="dei_EntityTaxIdentificationNumber_lbl" xlink:role="http://www.xbrl.org/2003/role/label">Entity Tax Identification Number</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="dei_EntityTaxIdentificationNumber_lbl" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Entity Tax Identification Number</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_IncomeStatementLocationAxis_lbl" xlink:role="http://www.xbrl.org/2003/role/label">Income Statement Location [Axis]</link:label>
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    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_CommonStockValue_lbl" xlink:role="http://www.xbrl.org/2003/role/totalLabel">Common Stock, Value, Issued, Total</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_CommonStockValue_lbl" xlink:role="http://www.xbrl.org/2003/role/label">Common Stock, Value, Issued</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_CommonStockValue_lbl" xlink:role="http://www.xbrl.org/2003/role/periodEndLabel">Common Stock, Value, Issued, Ending Balance</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_RetainedEarningsAccumulatedDeficit_lbl" xlink:role="http://www.xbrl.org/2003/role/periodEndLabel">Retained Earnings (Accumulated Deficit), Ending Balance</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_RetainedEarningsAccumulatedDeficit_lbl" xlink:role="http://www.xbrl.org/2003/role/periodStartLabel">Retained Earnings (Accumulated Deficit), Beginning Balance</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_RetainedEarningsAccumulatedDeficit_lbl" xlink:role="http://www.xbrl.org/2003/role/totalLabel">Retained Earnings (Accumulated Deficit), Total</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_RetainedEarningsAccumulatedDeficit_lbl" xlink:role="http://www.xbrl.org/2003/role/label">Retained Earnings (Accumulated Deficit)</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_RetainedEarningsAccumulatedDeficit_lbl" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Accumulated deficit</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="clsd_TwoThousandSixteenEmployeeStockPurchasePlanMember_lbl" xlink:role="http://www.xbrl.org/2003/role/verboseLabel">2016 Employee Stock Purchase Plan</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="clsd_TwoThousandSixteenEmployeeStockPurchasePlanMember_lbl" xlink:role="http://www.xbrl.org/2003/role/documentation">Two thousand sixteen employee stock purchase plan.</link:label>
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    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="clsd_TwoThousandSixteenEmployeeStockPurchasePlanMember_lbl" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Two Thousand Sixteen Employee Stock Purchase Plan</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_StatementEquityComponentsAxis_lbl" xlink:role="http://www.xbrl.org/2003/role/label">Equity Components [Axis]</link:label>
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    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="clsd_AccruedResearchAndDevelopmentExpenses_lbl" xlink:role="http://www.xbrl.org/2003/role/documentation">Accrued research and development expenses.</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="clsd_AccruedResearchAndDevelopmentExpenses_lbl" xlink:role="http://www.xbrl.org/2003/role/label">Accrued Research And Development Expenses</link:label>
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    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="clsd_SiliconValleyBankMidCapFundingXIITrustAndMidCapFinancialTrustMember_lbl" xlink:role="http://www.xbrl.org/2003/role/documentation">Silicon Valley Bank, MidCap funding XII trust and MidCap financial trust.</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="clsd_SiliconValleyBankMidCapFundingXIITrustAndMidCapFinancialTrustMember_lbl" xlink:role="http://www.xbrl.org/2003/role/label">Silicon Valley Bank Mid Cap Funding X I I Trust And Mid Cap Financial Trust [Member]</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="clsd_SiliconValleyBankMidCapFundingXIITrustAndMidCapFinancialTrustMember_lbl" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Silicon Valley Bank , MidCap Funding XII Trust and MidCap Financial Trust</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_CashAndCashEquivalentsPolicyTextBlock_lbl" xlink:role="http://www.xbrl.org/2003/role/label">Cash and Cash Equivalents, Policy [Policy Text Block]</link:label>
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    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_PrepaidExpenseCurrent_lbl" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Prepaid expenses</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_DebtInstrumentsAbstract_lbl" xlink:role="http://www.xbrl.org/2003/role/label">Debt Instruments [Abstract]</link:label>
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    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="dei_EntityEmergingGrowthCompany_lbl" xlink:role="http://www.xbrl.org/2003/role/label">Entity Emerging Growth Company</link:label>
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    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="clsd_DebtRelatedCommitmentFeesAndDebtRelatedIssuanceCosts_lbl" xlink:role="http://www.xbrl.org/2003/role/documentation">Debt related commitment fees and debt related issuance costs.</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="clsd_LicenseArrangementMember_lbl" xlink:role="http://www.xbrl.org/2003/role/terseLabel">License Arrangement</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="clsd_LicenseArrangementMember_lbl" xlink:role="http://www.xbrl.org/2003/role/label">License Arrangement [Member]</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="clsd_LicenseArrangementMember_lbl" xlink:role="http://www.xbrl.org/2003/role/documentation">License Arrangement member.</link:label>
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    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="dei_DocumentTransitionReport_lbl" xlink:role="http://www.xbrl.org/2003/role/label">Document Transition Report</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="dei_DocumentTransitionReport_lbl" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Document Transition Report</link:label>
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    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_AssetsFairValueDisclosure_lbl" xlink:role="http://www.xbrl.org/2003/role/label">Assets, Fair Value Disclosure</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_AssetsFairValueDisclosure_lbl" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Total financial assets</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriodWeightedAverageGrantDateFairValue_lbl" xlink:role="http://www.xbrl.org/2003/role/label">Share-Based Compensation Arrangement by Share-Based Payment Award, Equity Instruments Other than Options, Grants in Period, Weighted Average Grant Date Fair Value</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriodWeightedAverageGrantDateFairValue_lbl" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Weighted Average Exercise Price, Granted</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_AccountsPayableAccruedLiabilitiesAndOtherLiabilitiesDisclosureCurrentTextBlock_lbl" xlink:role="http://www.xbrl.org/2003/role/label">Accounts Payable, Accrued Liabilities, and Other Liabilities Disclosure, Current [Text Block]</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_AccountsPayableAccruedLiabilitiesAndOtherLiabilitiesDisclosureCurrentTextBlock_lbl" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Accrued Liabilities</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_StockIssuedDuringPeriodSharesRestrictedStockAwardNetOfForfeitures_lbl" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Vesting and settlement of restricted stock units, shares</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_StockIssuedDuringPeriodSharesRestrictedStockAwardNetOfForfeitures_lbl" xlink:role="http://www.xbrl.org/2003/role/totalLabel">Stock Issued During Period, Shares, Restricted Stock Award, Net of Forfeitures, Total</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_StockIssuedDuringPeriodSharesRestrictedStockAwardNetOfForfeitures_lbl" xlink:role="http://www.xbrl.org/2003/role/label">Stock Issued During Period, Shares, Restricted Stock Award, Net of Forfeitures</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_CommitmentsAndContingenciesDisclosureTextBlock_lbl" xlink:role="http://www.xbrl.org/2003/role/label">Commitments and Contingencies Disclosure [Text Block]</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_CommitmentsAndContingenciesDisclosureTextBlock_lbl" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Commitments and Contingencies</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardOptionsExercisesInPeriodWeightedAverageExercisePrice_lbl" xlink:role="http://www.xbrl.org/2003/role/label">Share-Based Compensation Arrangements by Share-Based Payment Award, Options, Exercises in Period, Weighted Average Exercise Price</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardOptionsExercisesInPeriodWeightedAverageExercisePrice_lbl" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Weighted Average Exercise Price, Exercised</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="dei_EntityCommonStockSharesOutstanding_lbl" xlink:role="http://www.xbrl.org/2003/role/label">Entity Common Stock, Shares Outstanding</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="dei_EntityCommonStockSharesOutstanding_lbl" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Entity Common Stock, Shares Outstanding</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_ResearchAndDevelopmentArrangementContractToPerformForOthersLineItems_lbl" xlink:role="http://www.xbrl.org/2003/role/label">Research and Development Arrangement, Contract to Perform for Others [Line Items]</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_ResearchAndDevelopmentArrangementContractToPerformForOthersLineItems_lbl" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Research And Development Arrangement Contract To Perform For Others [Line Items]</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="clsd_LicenseAndOtherAgreementsDisclosureTextBlock_lbl" xlink:role="http://www.xbrl.org/2003/role/documentation">License and other agreements disclosure.</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="clsd_LicenseAndOtherAgreementsDisclosureTextBlock_lbl" xlink:role="http://www.xbrl.org/2003/role/label">License And Other Agreements Disclosure [Text Block]</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="clsd_LicenseAndOtherAgreementsDisclosureTextBlock_lbl" xlink:role="http://www.xbrl.org/2003/role/terseLabel">License and Other Agreements</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="clsd_InitialProceedsFromRoyaltyPurchaseAndSalesAgreement_lbl" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Initial proceeds from royalty purchase and sales agreement</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="clsd_InitialProceedsFromRoyaltyPurchaseAndSalesAgreement_lbl" xlink:role="http://www.xbrl.org/2003/role/label">Initial Proceeds From Royalty Purchase and Sales Agreement</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="clsd_InitialProceedsFromRoyaltyPurchaseAndSalesAgreement_lbl" xlink:role="http://www.xbrl.org/2003/role/documentation">Initial proceeds from royalty purchase and sales agreement.</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_AmortizationOfFinancingCosts_lbl" xlink:role="http://www.xbrl.org/2003/role/label">Amortization of Debt Issuance Costs</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_AmortizationOfFinancingCosts_lbl" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Accretion of deferred debt issuance costs</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_PrincipalAmountOutstandingOnLoansSecuritized_lbl" xlink:role="http://www.xbrl.org/2003/role/label">Principal Amount Outstanding on Loans Securitized or Asset-Backed Financing Arrangement</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_PrincipalAmountOutstandingOnLoansSecuritized_lbl" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Aggregate principal amount</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_NetIncomeLoss_lbl" xlink:role="http://www.xbrl.org/2009/role/negatedLabel">Net loss</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_NetIncomeLoss_lbl" xlink:role="http://www.xbrl.org/2003/role/label">Net Income (Loss) Attributable to Parent</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_NetIncomeLoss_lbl" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Net loss</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_NetIncomeLoss_lbl" xlink:role="http://www.xbrl.org/2003/role/totalLabel">Net loss</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_OperatingLeaseLiabilityCurrent_lbl" xlink:role="http://www.xbrl.org/2003/role/label">Operating Lease, Liability, Current</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_OperatingLeaseLiabilityCurrent_lbl" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Current portion of operating lease liabilities</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="clsd_ThresholdPercentageOfSalesForTieredRoyalties_lbl" xlink:role="http://www.xbrl.org/2003/role/documentation">Threshold percentage of sales for tiered royalties.</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="clsd_ThresholdPercentageOfSalesForTieredRoyalties_lbl" xlink:role="http://www.xbrl.org/2003/role/label">Threshold Percentage Of Sales For Tiered Royalties</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="clsd_ThresholdPercentageOfSalesForTieredRoyalties_lbl" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Threshold percentage of sales for tiered royalties</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_AdditionalPaidInCapitalMember_lbl" xlink:role="http://www.xbrl.org/2003/role/label">Additional Paid-in Capital [Member]</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_AdditionalPaidInCapitalMember_lbl" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Additional Paid-In-Capital</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_ArrangementsAndNonarrangementTransactionsMember_lbl" xlink:role="http://www.xbrl.org/2003/role/label">Collaborative Arrangement and Arrangement Other than Collaborative [Domain]</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="dei_EntityRegistrantName_lbl" xlink:role="http://www.xbrl.org/2003/role/label">Entity Registrant Name</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="dei_EntityRegistrantName_lbl" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Entity Registrant Name</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_CashAndCashEquivalentsAtCarryingValue_lbl" xlink:role="http://www.xbrl.org/2003/role/periodStartLabel">Cash and Cash Equivalents, at Carrying Value, Beginning Balance</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_CashAndCashEquivalentsAtCarryingValue_lbl" xlink:role="http://www.xbrl.org/2003/role/totalLabel">Cash and Cash Equivalents, at Carrying Value, Total</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_CashAndCashEquivalentsAtCarryingValue_lbl" xlink:role="http://www.xbrl.org/2003/role/label">Cash and Cash Equivalents, at Carrying Value</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_CashAndCashEquivalentsAtCarryingValue_lbl" xlink:role="http://www.xbrl.org/2003/role/periodEndLabel">Cash and cash equivalents</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_CashAndCashEquivalentsAtCarryingValue_lbl" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Cash and cash equivalents</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_CashAndCashEquivalentsAtCarryingValue_lbl" xlink:role="http://www.xbrl.org/2003/role/verboseLabel">Cash and cash equivalents</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_EarningsPerShareTextBlock_lbl" xlink:role="http://www.xbrl.org/2003/role/label">Earnings Per Share [Text Block]</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_EarningsPerShareTextBlock_lbl" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Net Loss Per Share</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_DebtInstrumentMaturityDate_lbl" xlink:role="http://www.xbrl.org/2003/role/label">Debt Instrument, Maturity Date</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_DebtInstrumentMaturityDate_lbl" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Loans held-for-sale, maturity date</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_DebtInstrumentMaturityDate_lbl" xlink:role="http://www.xbrl.org/2003/role/verboseLabel">Note, Maturity date</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_ShareBasedCompensation_lbl" xlink:role="http://www.xbrl.org/2003/role/totalLabel">Share-based Payment Arrangement, Noncash Expense, Total</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_ShareBasedCompensation_lbl" xlink:role="http://www.xbrl.org/2003/role/label">Share-Based Payment Arrangement, Noncash Expense</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_ShareBasedCompensation_lbl" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Share-based compensation expense</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_AssetAcquisitionDomain_lbl" xlink:role="http://www.xbrl.org/2003/role/label">Asset Acquisition [Domain]</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_PropertyPlantAndEquipmentNet_lbl" xlink:role="http://www.xbrl.org/2003/role/periodEndLabel">Property, Plant and Equipment, Net, Ending Balance</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_PropertyPlantAndEquipmentNet_lbl" xlink:role="http://www.xbrl.org/2003/role/periodStartLabel">Property, Plant and Equipment, Net, Beginning Balance</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_PropertyPlantAndEquipmentNet_lbl" xlink:role="http://www.xbrl.org/2003/role/label">Property, Plant and Equipment, Net</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_PropertyPlantAndEquipmentNet_lbl" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Property and equipment, net</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_PropertyPlantAndEquipmentNet_lbl" xlink:role="http://www.xbrl.org/2003/role/totalLabel">Property and equipment, net</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_lbl" xlink:role="http://www.xbrl.org/2003/role/label">Award Type [Domain]</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_lbl" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Award Type</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_StatementLineItems_lbl" xlink:role="http://www.xbrl.org/2003/role/label">Statement [Line Items]</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_StatementLineItems_lbl" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Statement [Line Items]</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="clsd_AreaOfLeasedOfficeSpace_lbl" xlink:role="http://www.xbrl.org/2003/role/documentation">Square footage of leased office space.</link:label>
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    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="clsd_NonCashInterestExpenseOnSalesOfFutureRoyalties_lbl" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Non-cash interest expense on liability related to the sales of future royalties</link:label>
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    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="clsd_NonCashInterestExpenseOnSalesOfFutureRoyalties_lbl" xlink:role="http://www.xbrl.org/2003/role/documentation">Non cash interest expense on sales of future royalties.</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="dei_Security12bTitle_lbl" xlink:role="http://www.xbrl.org/2003/role/label">Title of 12(b) Security</link:label>
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    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_CommonStockMember_lbl" xlink:role="http://www.xbrl.org/2003/role/label">Common Stock [Member]</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_CommonStockMember_lbl" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Common Stock</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="clsd_ProceedsFromIssuanceAtTheMarket_lbl" xlink:role="http://www.xbrl.org/2003/role/documentation">Proceeds from the issuance of shares under an at-the-market sales agreement.</link:label>
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    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_NetCashProvidedByUsedInOperatingActivitiesAbstract_lbl" xlink:role="http://www.xbrl.org/2003/role/label">Net Cash Provided by (Used in) Operating Activities [Abstract]</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_NetCashProvidedByUsedInOperatingActivitiesAbstract_lbl" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Operating activities</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_EquityComponentDomain_lbl" xlink:role="http://www.xbrl.org/2003/role/label">Equity Component [Domain]</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_EquityComponentDomain_lbl" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Equity Component</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_RevenueFromContractWithCustomerExcludingAssessedTax_lbl" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Revenue</link:label>
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    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="dei_EntityAddressStateOrProvince_lbl" xlink:role="http://www.xbrl.org/2003/role/label">Entity Address, State or Province</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="dei_EntityAddressStateOrProvince_lbl" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Entity Address, State or Province</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="clsd_FirstMilestoneProceedsFromRoyaltyPurchaseAndSaleAgreement_lbl" xlink:role="http://www.xbrl.org/2003/role/label">First Milestone Proceeds From Royalty Purchase And Sale Agreement</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="clsd_FirstMilestoneProceedsFromRoyaltyPurchaseAndSaleAgreement_lbl" xlink:role="http://www.xbrl.org/2003/role/documentation">First Milestone Proceeds From Royalty Purchase And Sale Agreement</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="srt_StatementGeographicalAxis_lbl" xlink:role="http://www.xbrl.org/2003/role/label">Geographical [Axis]</link:label>
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    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="dei_DocumentType_lbl" xlink:role="http://www.xbrl.org/2003/role/label">Document Type</link:label>
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    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="dei_EntityShellCompany_lbl" xlink:role="http://www.xbrl.org/2003/role/label">Entity Shell Company</link:label>
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    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisLineItems_lbl" xlink:role="http://www.xbrl.org/2003/role/label">Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisLineItems_lbl" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="clsd_CommitmentAndContingenciesTable_lbl" xlink:role="http://www.xbrl.org/2003/role/documentation">Commitment and Contingencies [Table]</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="clsd_CommitmentAndContingenciesTable_lbl" xlink:role="http://www.xbrl.org/2003/role/label">Commitment And Contingencies [Table]</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="clsd_CommitmentAndContingenciesTable_lbl" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Commitment And Contingencies [Table]</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisTable_lbl" xlink:role="http://www.xbrl.org/2003/role/label">Fair Value, Recurring and Nonrecurring [Table]</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisTable_lbl" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Table]</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="clsd_StockIssuedDuringPeriodSharesAtMarketSalesAgreement_lbl" xlink:role="http://www.xbrl.org/2003/role/documentation">Stock issued during period shares at market sales agreement.</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="clsd_StockIssuedDuringPeriodSharesAtMarketSalesAgreement_lbl" xlink:role="http://www.xbrl.org/2003/role/label">Stock Issued During Period Shares At Market Sales Agreement</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="clsd_StockIssuedDuringPeriodSharesAtMarketSalesAgreement_lbl" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Issuance of common shares under at-the-market sales agreement, shares</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_AccountsReceivableSale_lbl" xlink:role="http://www.xbrl.org/2003/role/label">Accounts Receivable, Sale</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_AccountsReceivableSale_lbl" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Rights sold</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="dei_SecurityExchangeName_lbl" xlink:role="http://www.xbrl.org/2003/role/label">Security Exchange Name</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="dei_SecurityExchangeName_lbl" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Security Exchange Name</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_RevenueRecognitionMilestoneMethodMilestone_lbl" xlink:role="http://www.xbrl.org/2003/role/label">Revenue Recognition, Milestone Method, Milestone</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_RevenueRecognitionMilestoneMethodMilestone_lbl" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Additional amount sales milestone achieved</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_ClassOfStockLineItems_lbl" xlink:role="http://www.xbrl.org/2003/role/label">Class of Stock [Line Items]</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareLineItems_lbl" xlink:role="http://www.xbrl.org/2003/role/label">Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareLineItems_lbl" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_SignificantAccountingPoliciesTextBlock_lbl" xlink:role="http://www.xbrl.org/2003/role/label">Significant Accounting Policies [Text Block]</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_SignificantAccountingPoliciesTextBlock_lbl" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Significant Accounting Policies</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_NetCashProvidedByUsedInOperatingActivities_lbl" xlink:role="http://www.xbrl.org/2003/role/label">Net Cash Provided by (Used in) Operating Activities</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_NetCashProvidedByUsedInOperatingActivities_lbl" xlink:role="http://www.xbrl.org/2003/role/totalLabel">Net cash used in operating activities</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_EmployeeServiceShareBasedCompensationNonvestedAwardsTotalCompensationCostNotYetRecognizedPeriodForRecognition1_lbl" xlink:role="http://www.xbrl.org/2003/role/label">Share-Based Payment Arrangement, Nonvested Award, Cost Not yet Recognized, Period for Recognition</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_EmployeeServiceShareBasedCompensationNonvestedAwardsTotalCompensationCostNotYetRecognizedPeriodForRecognition1_lbl" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Expected to be recognized over a weighted average period</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_DebtInstrumentInterestRateEffectivePercentage_lbl" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Effective interest rate</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_DebtInstrumentInterestRateEffectivePercentage_lbl" xlink:role="http://www.xbrl.org/2003/role/label">Debt Instrument, Interest Rate, Effective Percentage</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_CommitmentsAndContingenciesDisclosureAbstract_lbl" xlink:role="http://www.xbrl.org/2003/role/label">Commitments and Contingencies Disclosure [Abstract]</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_OperatingLeaseCost_lbl" xlink:role="http://www.xbrl.org/2003/role/label">Operating Lease, Cost</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_OperatingLeaseCost_lbl" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Operating Lease, Cost</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_RestrictedStockUnitsRSUMember_lbl" xlink:role="http://www.xbrl.org/2003/role/label">Restricted Stock Units (RSUs) [Member]</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_RestrictedStockUnitsRSUMember_lbl" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Restricted Stock Units (RSUs)</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_LesseeOperatingLeaseLiabilityMaturityTableTextBlock_lbl" xlink:role="http://www.xbrl.org/2003/role/label">Lessee, Operating Lease, Liability, Maturity [Table Text Block]</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_LesseeOperatingLeaseLiabilityMaturityTableTextBlock_lbl" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Future Minimum Commitments Due Under Non-Cancelable Operating Leases</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_WarrantMember_lbl" xlink:role="http://www.xbrl.org/2003/role/label">Warrant [Member]</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_WarrantMember_lbl" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Stock Purchase Warrants</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_ScheduleOfShareBasedCompensationStockOptionsActivityTableTextBlock_lbl" xlink:role="http://www.xbrl.org/2003/role/label">Share-Based Payment Arrangement, Option, Activity [Table Text Block]</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_ScheduleOfShareBasedCompensationStockOptionsActivityTableTextBlock_lbl" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Summary of Activity Related to Stock Options</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_NewAccountingPronouncementsPolicyPolicyTextBlock_lbl" xlink:role="http://www.xbrl.org/2003/role/label">New Accounting Pronouncements, Policy [Policy Text Block]</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_NewAccountingPronouncementsPolicyPolicyTextBlock_lbl" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Recent Accounting Pronouncements</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_CommonStockSharesOutstanding_lbl" xlink:role="http://www.xbrl.org/2003/role/periodEndLabel">Common Stock, Shares, Outstanding, Ending Balance</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_CommonStockSharesOutstanding_lbl" xlink:role="http://www.xbrl.org/2003/role/periodStartLabel">Common Stock, Shares, Outstanding, Beginning Balance</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_CommonStockSharesOutstanding_lbl" xlink:role="http://www.xbrl.org/2003/role/label">Common Stock, Shares, Outstanding</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_CommonStockSharesOutstanding_lbl" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Common stock, shares outstanding</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_CommonStockSharesOutstanding_lbl" xlink:role="http://www.xbrl.org/2003/role/verboseLabel">Common stock, shares outstanding</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_GainsLossesOnExtinguishmentOfDebt_lbl" xlink:role="http://www.xbrl.org/2009/role/negatedTerseLabel">Gain on extinguishment of debt</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_GainsLossesOnExtinguishmentOfDebt_lbl" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Gain (loss) on extinguishment of debt</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_GainsLossesOnExtinguishmentOfDebt_lbl" xlink:role="http://www.xbrl.org/2003/role/totalLabel">Gain (Loss) on Extinguishment of Debt, Total</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_GainsLossesOnExtinguishmentOfDebt_lbl" xlink:role="http://www.xbrl.org/2003/role/label">Gain (Loss) on Extinguishment of Debt</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_DebtDisclosureTextBlock_lbl" xlink:role="http://www.xbrl.org/2003/role/terseLabel">CARES Act Paycheck Protection Program Loan</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_DebtDisclosureTextBlock_lbl" xlink:role="http://www.xbrl.org/2003/role/label">Debt Disclosure [Text Block]</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_FairValueInputsLevel2Member_lbl" xlink:role="http://www.xbrl.org/2003/role/label">Fair Value, Inputs, Level 2 [Member]</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_FairValueInputsLevel2Member_lbl" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Level 2</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_DeferredRevenueCurrent_lbl" xlink:role="http://www.xbrl.org/2003/role/verboseLabel">Deferred revenue</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_DeferredRevenueCurrent_lbl" xlink:role="http://www.xbrl.org/2003/role/totalLabel">Deferred Revenue, Current, Total</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_DeferredRevenueCurrent_lbl" xlink:role="http://www.xbrl.org/2003/role/label">Deferred Revenue, Current</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_DeferredRevenueCurrent_lbl" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Deferred revenue</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_NetCashProvidedByUsedInInvestingActivitiesAbstract_lbl" xlink:role="http://www.xbrl.org/2003/role/label">Net Cash Provided by (Used in) Investing Activities [Abstract]</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_NetCashProvidedByUsedInInvestingActivitiesAbstract_lbl" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Investing activities</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_CommitmentsAndContingencies_lbl" xlink:role="http://www.xbrl.org/2003/role/label">Commitments and Contingencies</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_CommitmentsAndContingencies_lbl" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Commitments and contingencies</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_CommonStockSharesIssued_lbl" xlink:role="http://www.xbrl.org/2003/role/totalLabel">Common Stock, Shares, Issued, Total</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_CommonStockSharesIssued_lbl" xlink:role="http://www.xbrl.org/2003/role/label">Common Stock, Shares, Issued</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_CommonStockSharesIssued_lbl" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Common stock, shares, issued</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_LiabilitiesAbstract_lbl" xlink:role="http://www.xbrl.org/2003/role/label">Liabilities [Abstract]</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_LiabilitiesAbstract_lbl" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Liabilities</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="clsd_StockPurchaseWarrantsAbstract_lbl" xlink:role="http://www.xbrl.org/2003/role/documentation">Stock purchase warrants.</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="clsd_StockPurchaseWarrantsAbstract_lbl" xlink:role="http://www.xbrl.org/2003/role/label">Stock Purchase Warrants [Abstract]</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="srt_MinimumMember_lbl" xlink:role="http://www.xbrl.org/2003/role/label">Minimum [Member]</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="srt_MinimumMember_lbl" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Minimum</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="srt_MinimumMember_lbl" xlink:role="http://www.xbrl.org/2003/role/verboseLabel">Minimum</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="clsd_LiabilitiesRelatedToTheSalesOfFutureRoyalties_lbl" xlink:role="http://www.xbrl.org/2003/role/verboseLabel">Balance at September 30, 2022</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="clsd_LiabilitiesRelatedToTheSalesOfFutureRoyalties_lbl" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Liability related to the sales of future royalties, net</link:label>
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    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="clsd_LiabilitiesRelatedToTheSalesOfFutureRoyalties_lbl" xlink:role="http://www.xbrl.org/2003/role/documentation">Liabilities Related To The Sales Of Future Royalties</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="clsd_IssuanceOfCommonSharesUnderADirectRegisteredOffering_lbl" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Issuance of common shares under a direct registered offering, shares</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="clsd_IssuanceOfCommonSharesUnderADirectRegisteredOffering_lbl" xlink:role="http://www.xbrl.org/2003/role/label">Issuance of common shares under a direct registered offering</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="clsd_IssuanceOfCommonSharesUnderADirectRegisteredOffering_lbl" xlink:role="http://www.xbrl.org/2003/role/documentation">Issuance of common shares under a direct registered offering</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="clsd_OperatingLeasesRentExpenseMinimumRentalsPerMonth_lbl" xlink:role="http://www.xbrl.org/2003/role/documentation">Operating leases rent expense minimum rentals per month.</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="clsd_OperatingLeasesRentExpenseMinimumRentalsPerMonth_lbl" xlink:role="http://www.xbrl.org/2003/role/label">Operating Leases Rent Expense Minimum Rentals Per Month</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="clsd_OperatingLeasesRentExpenseMinimumRentalsPerMonth_lbl" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Minimum monthly lease payments</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsExercisableWeightedAverageExercisePrice_lbl" xlink:role="http://www.xbrl.org/2003/role/label">Share-Based Compensation Arrangement by Share-Based Payment Award, Options, Exercisable, Weighted Average Exercise Price</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsExercisableWeightedAverageExercisePrice_lbl" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Weighted Average Exercise Price, Options exercisable</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_ProceedsFromLicenseFeesReceived_lbl" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Aggregate milestone payments from the licensees</link:label>
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    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_DeferredRevenueArrangementTypeDomain_lbl" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Deferred Revenue</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_DebtInstrumentAxis_lbl" xlink:role="http://www.xbrl.org/2003/role/label">Debt Instrument [Axis]</link:label>
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    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_StockholdersEquityAbstract_lbl" xlink:role="http://www.xbrl.org/2003/role/label">Stockholders' Equity Attributable to Parent [Abstract]</link:label>
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    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_RestrictedCashAndCashEquivalentsNoncurrent_lbl" xlink:role="http://www.xbrl.org/2003/role/totalLabel">Restricted Cash and Cash Equivalents, Noncurrent, Total</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_RestrictedCashAndCashEquivalentsNoncurrent_lbl" xlink:role="http://www.xbrl.org/2003/role/label">Restricted Cash and Cash Equivalents, Noncurrent</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_RestrictedCashAndCashEquivalentsNoncurrent_lbl" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Restricted cash</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsForfeituresWeightedAverageGrantDateFairValue_lbl" xlink:role="http://www.xbrl.org/2003/role/label">Share-Based Compensation Arrangement by Share-Based Payment Award, Equity Instruments Other than Options, Forfeitures, Weighted Average Grant Date Fair Value</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsForfeituresWeightedAverageGrantDateFairValue_lbl" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Weighted Average Exercise Price, Forfeited</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_AwardTypeAxis_lbl" xlink:role="http://www.xbrl.org/2003/role/label">Award Type [Axis]</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_AwardTypeAxis_lbl" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Award Type</link:label>
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    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_SubsequentEventMember_lbl" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Subsequent Event</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="clsd_InitialProceedsFromRoyaltySaleAndPurchaseAgreementNetOfCertainExpenses_lbl" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Initial payment</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="clsd_InitialProceedsFromRoyaltySaleAndPurchaseAgreementNetOfCertainExpenses_lbl" xlink:role="http://www.xbrl.org/2003/role/label">Initial Proceeds From Royalty Sale and Purchase Agreement Net of Certain Expenses</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="clsd_InitialProceedsFromRoyaltySaleAndPurchaseAgreementNetOfCertainExpenses_lbl" xlink:role="http://www.xbrl.org/2003/role/documentation">Initial proceeds from royalty sale and purchase agreement net of certain expenses.</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="clsd_AdditionalFeesForExpansionToExistingLicense_lbl" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Additional fees for expansion to existing license</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="clsd_AdditionalFeesForExpansionToExistingLicense_lbl" xlink:role="http://www.xbrl.org/2003/role/label">Additional fees for expansion to existing license</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="clsd_AdditionalFeesForExpansionToExistingLicense_lbl" xlink:role="http://www.xbrl.org/2003/role/documentation">Additional fees for expansion to existing license.</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="clsd_ProceedsFromRoyaltyPurchaseAndSaleAgreementNetOfIssuanceCosts_lbl" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Proceeds from royalty purchase and sale agreement</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="clsd_ProceedsFromRoyaltyPurchaseAndSaleAgreementNetOfIssuanceCosts_lbl" xlink:role="http://www.xbrl.org/2009/role/negatedLabel">Proceeds from royalty purchase and sale agreement, net of issuance costs</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="clsd_ProceedsFromRoyaltyPurchaseAndSaleAgreementNetOfIssuanceCosts_lbl" xlink:role="http://www.xbrl.org/2003/role/label">Proceeds from royalty purchase and sale agreement, net of issuance costs</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="clsd_ProceedsFromRoyaltyPurchaseAndSaleAgreementNetOfIssuanceCosts_lbl" xlink:role="http://www.xbrl.org/2003/role/documentation">Proceeds from royalty purchase and sale agreement, net of issuance costs</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_ResearchAndDevelopmentExpense_lbl" xlink:role="http://www.xbrl.org/2003/role/totalLabel">Research and Development Expense, Total</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_ResearchAndDevelopmentExpense_lbl" xlink:role="http://www.xbrl.org/2003/role/label">Research and Development Expense</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_ResearchAndDevelopmentExpense_lbl" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Research and development</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_LesseeOperatingLeaseTermOfContract_lbl" xlink:role="http://www.xbrl.org/2003/role/label">Lessee, Operating Lease, Term of Contract</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_LesseeOperatingLeaseTermOfContract_lbl" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Operating lease agreement term</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="dei_EntityCentralIndexKey_lbl" xlink:role="http://www.xbrl.org/2003/role/label">Entity Central Index Key</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="dei_EntityCentralIndexKey_lbl" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Entity Central Index Key</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="clsd_RoyaltyPurchaseAndSaleAgreementTextBlock_lbl" xlink:role="http://www.xbrl.org/2003/role/label">Royalty Purchase and Sale Agreement [Text Block]</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="clsd_RoyaltyPurchaseAndSaleAgreementTextBlock_lbl" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Royalty Purchase and Sale Agreement</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="clsd_RoyaltyPurchaseAndSaleAgreementTextBlock_lbl" xlink:role="http://www.xbrl.org/2003/role/documentation">Royalty Purchase and Sale Agreement Text Block</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_AccountingPoliciesAbstract_lbl" xlink:role="http://www.xbrl.org/2003/role/label">Accounting Policies [Abstract]</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_AccumulatedDepreciationDepletionAndAmortizationPropertyPlantAndEquipment_lbl" xlink:role="http://www.xbrl.org/2003/role/periodEndLabel">Accumulated Depreciation, Depletion and Amortization, Property, Plant, and Equipment, Ending Balance</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_AccumulatedDepreciationDepletionAndAmortizationPropertyPlantAndEquipment_lbl" xlink:role="http://www.xbrl.org/2003/role/periodStartLabel">Accumulated Depreciation, Depletion and Amortization, Property, Plant, and Equipment, Beginning Balance</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_AccumulatedDepreciationDepletionAndAmortizationPropertyPlantAndEquipment_lbl" xlink:role="http://www.xbrl.org/2003/role/totalLabel">Accumulated Depreciation, Depletion and Amortization, Property, Plant, and Equipment, Total</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_AccumulatedDepreciationDepletionAndAmortizationPropertyPlantAndEquipment_lbl" xlink:role="http://www.xbrl.org/2003/role/label">Accumulated Depreciation, Depletion and Amortization, Property, Plant, and Equipment</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_AccumulatedDepreciationDepletionAndAmortizationPropertyPlantAndEquipment_lbl" xlink:role="http://www.xbrl.org/2009/role/negatedLabel">Less: Accumulated depreciation</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_ScheduleOfPropertyPlantAndEquipmentTable_lbl" xlink:role="http://www.xbrl.org/2003/role/label">Property, Plant and Equipment [Table]</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_ScheduleOfPropertyPlantAndEquipmentTable_lbl" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Schedule Of Property Plant And Equipment [Table]</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_DisclosureOfCompensationRelatedCostsShareBasedPaymentsTextBlock_lbl" xlink:role="http://www.xbrl.org/2003/role/label">Share-Based Payment Arrangement [Text Block]</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_DisclosureOfCompensationRelatedCostsShareBasedPaymentsTextBlock_lbl" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Share-Based Compensation</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_GeneralAndAdministrativeExpense_lbl" xlink:role="http://www.xbrl.org/2003/role/totalLabel">General and Administrative Expense, Total</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_GeneralAndAdministrativeExpense_lbl" xlink:role="http://www.xbrl.org/2003/role/label">General and Administrative Expense</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_GeneralAndAdministrativeExpense_lbl" xlink:role="http://www.xbrl.org/2003/role/terseLabel">General and administrative</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="clsd_MilestoneProceedsFromRoyaltyPurchaseAndSaleAgreement_lbl" xlink:role="http://www.xbrl.org/2003/role/documentation">Milestone Proceeds From Royalty Purchase And Sale Agreement</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="clsd_MilestoneProceedsFromRoyaltyPurchaseAndSaleAgreement_lbl" xlink:role="http://www.xbrl.org/2003/role/label">Milestone Proceeds From Royalty Purchase And Sale Agreement</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="clsd_MilestoneProceedsFromRoyaltyPurchaseAndSaleAgreement_lbl" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Milestone proceeds from royalty purchase and sale agreement</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="clsd_AdditionalProceedsFromRoyaltyPurchaseAndSaleAgreement_lbl" xlink:role="http://www.xbrl.org/2003/role/documentation">Additional Proceeds From Royalty Purchase And Sale Agreement</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="clsd_AdditionalProceedsFromRoyaltyPurchaseAndSaleAgreement_lbl" xlink:role="http://www.xbrl.org/2003/role/label">Additional Proceeds From Royalty Purchase And Sale Agreement</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="clsd_AdditionalProceedsFromRoyaltyPurchaseAndSaleAgreement_lbl" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Additional proceeds from royalty purchase and sale agreement</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_OrganizationConsolidationAndPresentationOfFinancialStatementsAbstract_lbl" xlink:role="http://www.xbrl.org/2003/role/label">Organization, Consolidation and Presentation of Financial Statements [Abstract]</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingWeightedAverageExercisePrice_lbl" xlink:role="http://www.xbrl.org/2003/role/label">Share-Based Compensation Arrangement by Share-Based Payment Award, Options, Outstanding, Weighted Average Exercise Price</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingWeightedAverageExercisePrice_lbl" xlink:role="http://www.xbrl.org/2003/role/periodEndLabel">Weighted Average Exercise Price, Options outstanding, Ending balance</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingWeightedAverageExercisePrice_lbl" xlink:role="http://www.xbrl.org/2003/role/periodStartLabel">Weighted Average Exercise Price, Options outstanding, Beginning balance</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_ResearchAndDevelopmentExpenseMember_lbl" xlink:role="http://www.xbrl.org/2003/role/label">Research and Development Expense [Member]</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_ResearchAndDevelopmentExpenseMember_lbl" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Research and Development</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="clsd_WarrantsExpirationTerm_lbl" xlink:role="http://www.xbrl.org/2003/role/documentation">Warrants expiration term.</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="clsd_WarrantsExpirationTerm_lbl" xlink:role="http://www.xbrl.org/2003/role/label">Warrants Expiration Term</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="clsd_WarrantsExpirationTerm_lbl" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Warrants expiration term</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="clsd_ScheduleOfOperatingLeasesAssetsAndLiabilities_lbl" xlink:role="http://www.xbrl.org/2003/role/documentation">Schedule of operating leases assets and liabilities.</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="clsd_ScheduleOfOperatingLeasesAssetsAndLiabilities_lbl" xlink:role="http://www.xbrl.org/2003/role/label">Schedule Of Operating Leases Assets And Liabilities</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="clsd_ScheduleOfOperatingLeasesAssetsAndLiabilities_lbl" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Operating Leases Included on the Balance Sheet</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="clsd_PreLaunchMilestonePayments_lbl" xlink:role="http://www.xbrl.org/2003/role/documentation">Pre-Launch Milestone Payments.</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="clsd_PreLaunchMilestonePayments_lbl" xlink:role="http://www.xbrl.org/2003/role/label">Pre Launch Milestone Payments</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="clsd_PreLaunchMilestonePayments_lbl" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Pre-launch milestone payments</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="srt_ScenarioForecastMember_lbl" xlink:role="http://www.xbrl.org/2003/role/label">Forecast [Member]</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="srt_ScenarioForecastMember_lbl" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Forecast</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_AdjustmentsToReconcileNetIncomeLossToCashProvidedByUsedInOperatingActivitiesAbstract_lbl" xlink:role="http://www.xbrl.org/2003/role/label">Adjustments to Reconcile Net Income (Loss) to Cash Provided by (Used in) Operating Activities [Abstract]</link:label>
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    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_RetainedEarningsMember_lbl" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Accumulated Deficit</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="clsd_FirstAmendedAndRestatedLoanAndSecurityAgreementMember_lbl" xlink:role="http://www.xbrl.org/2003/role/documentation">First amended and restated loan and security agreement.</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="clsd_FirstAmendedAndRestatedLoanAndSecurityAgreementMember_lbl" xlink:role="http://www.xbrl.org/2003/role/label">First Amended And Restated Loan And Security Agreement [Member]</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="clsd_FirstAmendedAndRestatedLoanAndSecurityAgreementMember_lbl" xlink:role="http://www.xbrl.org/2003/role/terseLabel">First Amended and Restated Loan and Security Agreement</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="clsd_MilestonePaymentsReceived_lbl" xlink:role="http://www.xbrl.org/2003/role/verboseLabel">Milestone payments received</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="clsd_MilestonePaymentsReceived_lbl" xlink:role="http://www.xbrl.org/2003/role/label">Milestone Payments Received</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="clsd_MilestonePaymentsReceived_lbl" xlink:role="http://www.xbrl.org/2003/role/documentation">Milestone payments received.</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_EmployeeServiceShareBasedCompensationAllocationOfRecognizedPeriodCostsLineItems_lbl" xlink:role="http://www.xbrl.org/2003/role/label">Share-Based Payment Arrangement, Expensed and Capitalized, Amount [Line Items]</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_EmployeeServiceShareBasedCompensationAllocationOfRecognizedPeriodCostsLineItems_lbl" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Employee Service Share Based Compensation Allocation Of Recognized Period Costs [Line Items]</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="clsd_UnauditedInterimFinancialInformationPolicyTextBlock_lbl" xlink:role="http://www.xbrl.org/2003/role/documentation">Unaudited interim financial information.</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="clsd_UnauditedInterimFinancialInformationPolicyTextBlock_lbl" xlink:role="http://www.xbrl.org/2003/role/label">Unaudited Interim Financial Information Policy [Text Block]</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="clsd_UnauditedInterimFinancialInformationPolicyTextBlock_lbl" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Unaudited Interim Financial Information</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="clsd_InitialPayment_lbl" xlink:role="http://www.xbrl.org/2003/role/documentation">Initial payment</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="clsd_InitialPayment_lbl" xlink:role="http://www.xbrl.org/2003/role/label">Initial payment</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="clsd_InitialPayment_lbl" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Initial payment</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_ResearchAndDevelopmentArrangementContractToPerformForOthersByTypeAxis_lbl" xlink:role="http://www.xbrl.org/2003/role/label">Research and Development Arrangement, Contract to Perform for Others, Type [Axis]</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_ResearchAndDevelopmentArrangementContractToPerformForOthersByTypeAxis_lbl" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Research and Development Arrangement, Contract to Perform for Others, Type</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_CompensatingBalanceDescription_lbl" xlink:role="http://www.xbrl.org/2003/role/label">Compensating Balance, Description</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_CompensatingBalanceDescription_lbl" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Agreement expiration description</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_PropertyPlantAndEquipmentGross_lbl" xlink:role="http://www.xbrl.org/2003/role/periodEndLabel">Property, Plant and Equipment, Gross, Ending Balance</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_PropertyPlantAndEquipmentGross_lbl" xlink:role="http://www.xbrl.org/2003/role/periodStartLabel">Property, Plant and Equipment, Gross, Beginning Balance</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_PropertyPlantAndEquipmentGross_lbl" xlink:role="http://www.xbrl.org/2003/role/totalLabel">Property, Plant and Equipment, Gross, Total</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_PropertyPlantAndEquipmentGross_lbl" xlink:role="http://www.xbrl.org/2003/role/label">Property, Plant and Equipment, Gross</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_PropertyPlantAndEquipmentGross_lbl" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Property and Equipment, gross</link:label>
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    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_AdditionalPaidInCapital_lbl" xlink:role="http://www.xbrl.org/2003/role/periodStartLabel">Additional Paid in Capital, Beginning Balance</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_AdditionalPaidInCapital_lbl" xlink:role="http://www.xbrl.org/2003/role/totalLabel">Additional Paid in Capital, Total</link:label>
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    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_AdditionalPaidInCapital_lbl" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Additional paid-in capital</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_AccountsReceivableNet_lbl" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Accounts receivable</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_AccountsReceivableNet_lbl" xlink:role="http://www.xbrl.org/2003/role/label">Accounts Receivable, after Allowance for Credit Loss</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_AccountsReceivableNet_lbl" xlink:role="http://www.xbrl.org/2003/role/totalLabel">Accounts Receivable, after Allowance for Credit Loss, Total</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="dei_EntityInteractiveDataCurrent_lbl" xlink:role="http://www.xbrl.org/2003/role/label">Entity Interactive Data Current</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="dei_EntityInteractiveDataCurrent_lbl" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Entity Interactive Data Current</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="stpr_GA_lbl" xlink:role="http://www.xbrl.org/2003/role/label">GEORGIA</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="stpr_GA_lbl" xlink:role="http://www.xbrl.org/2003/role/terseLabel">GEORGIA</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="clsd_UpfrontPaymentMember_lbl" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Upfront Payment</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="clsd_UpfrontPaymentMember_lbl" xlink:role="http://www.xbrl.org/2003/role/documentation">Upfront payment member.</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="clsd_UpfrontPaymentMember_lbl" xlink:role="http://www.xbrl.org/2003/role/label">Upfront Payment [Member]</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="clsd_OperatingLeasesFutureMinimumPaymentDue_lbl" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Total minimum lease payments</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="clsd_OperatingLeasesFutureMinimumPaymentDue_lbl" xlink:role="http://www.xbrl.org/2003/role/label">Operating Leases Future Minimum Payment Due</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="clsd_OperatingLeasesFutureMinimumPaymentDue_lbl" xlink:role="http://www.xbrl.org/2003/role/documentation">Operating Leases Future Minimum Payment Due</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="clsd_OperatingLeasesFutureMinimumPaymentDue_lbl" xlink:role="http://www.xbrl.org/2003/role/totalLabel">Operating Leases Future Minimum Payment Due, Total</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="clsd_ArcticVisionsLimitedMember_lbl" xlink:role="http://www.xbrl.org/2003/role/documentation">Arctic Vision Limited [Member]</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="clsd_ArcticVisionsLimitedMember_lbl" xlink:role="http://www.xbrl.org/2003/role/label">Arctic Visions Limited [Member]</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="clsd_ArcticVisionsLimitedMember_lbl" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Arctic Vision Limited</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_LeaseholdImprovementsMember_lbl" xlink:role="http://www.xbrl.org/2003/role/label">Leasehold Improvements [Member]</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_LeaseholdImprovementsMember_lbl" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Leasehold Improvements</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="dei_LocalPhoneNumber_lbl" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Local Phone Number</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="dei_LocalPhoneNumber_lbl" xlink:role="http://www.xbrl.org/2003/role/label">Local Phone Number</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_DebtDisclosureAbstract_lbl" xlink:role="http://www.xbrl.org/2003/role/label">Debt Disclosure [Abstract]</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_lbl" xlink:role="http://www.xbrl.org/2003/role/label">Share-Based Compensation Arrangement by Share-Based Payment Award [Line Items]</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_lbl" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Share Based Compensation Arrangement By Share Based Payment Award [Line Items]</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_BasisOfAccountingPolicyPolicyTextBlock_lbl" xlink:role="http://www.xbrl.org/2003/role/label">Basis of Accounting, Policy [Policy Text Block]</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_BasisOfAccountingPolicyPolicyTextBlock_lbl" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Basis of Presentation</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsExercisableNumber_lbl" xlink:role="http://www.xbrl.org/2003/role/label">Share-Based Compensation Arrangement by Share-Based Payment Award, Options, Exercisable, Number</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsExercisableNumber_lbl" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Number of Shares, Options exercisable</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_RoyaltyIncomeNonoperating_lbl" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Royalty purchased</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_RoyaltyIncomeNonoperating_lbl" xlink:role="http://www.xbrl.org/2003/role/label">Royalty Income, Nonoperating</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_LineOfCreditFacilityAxis_lbl" xlink:role="http://www.xbrl.org/2003/role/label">Lender Name [Axis]</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_LineOfCreditFacilityAxis_lbl" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Lender Name</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsGrantsInPeriodGross_lbl" xlink:role="http://www.xbrl.org/2003/role/label">Share-Based Compensation Arrangement by Share-Based Payment Award, Options, Grants in Period, Gross</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsGrantsInPeriodGross_lbl" xlink:role="http://www.xbrl.org/2003/role/verboseLabel">Number of Shares, Granted</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="clsd_DevelopmentMilestonePayments_lbl" xlink:role="http://www.xbrl.org/2003/role/documentation">Development milestone payments.</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="clsd_DevelopmentMilestonePayments_lbl" xlink:role="http://www.xbrl.org/2003/role/label">Development Milestone Payments</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="clsd_DevelopmentMilestonePayments_lbl" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Development milestone payments</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_DebtInstrumentPaymentTerms_lbl" xlink:role="http://www.xbrl.org/2003/role/label">Debt Instrument, Payment Terms</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_DebtInstrumentPaymentTerms_lbl" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Debt Instrument, Payment Terms</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_IncomeStatementLocationDomain_lbl" xlink:role="http://www.xbrl.org/2003/role/label">Income Statement Location [Domain]</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_IncomeStatementLocationDomain_lbl" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Income Statement Location</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_PropertyPlantAndEquipmentAbstract_lbl" xlink:role="http://www.xbrl.org/2003/role/label">Property, Plant and Equipment [Abstract]</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedNumber_lbl" xlink:role="http://www.xbrl.org/2003/role/label">Share-Based Compensation Arrangement by Share-Based Payment Award, Equity Instruments Other than Options, Nonvested, Number</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedNumber_lbl" xlink:role="http://www.xbrl.org/2003/role/periodEndLabel">Non-vested units outstanding, Number of Shares, Ending balance</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedNumber_lbl" xlink:role="http://www.xbrl.org/2003/role/periodStartLabel">Non-vested units outstanding, Number of Shares, Beginning balance</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_LongTermDebt_lbl" xlink:role="http://www.xbrl.org/2003/role/totalLabel">Long-term Debt, Total</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_LongTermDebt_lbl" xlink:role="http://www.xbrl.org/2003/role/label">Long-Term Debt</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_LongTermDebt_lbl" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Long term debt</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_SharesOutstanding_lbl" xlink:role="http://www.xbrl.org/2003/role/label">Shares, Outstanding</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_SharesOutstanding_lbl" xlink:role="http://www.xbrl.org/2003/role/periodEndLabel">Ending balance, shares</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_SharesOutstanding_lbl" xlink:role="http://www.xbrl.org/2003/role/periodStartLabel">Beginning balance, shares</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_LineOfCreditFacilityRemainingBorrowingCapacity_lbl" xlink:role="http://www.xbrl.org/2003/role/label">Line of Credit Facility, Remaining Borrowing Capacity</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_LineOfCreditFacilityRemainingBorrowingCapacity_lbl" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Line of credit facility, remaining borrowing capacity</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_IncreaseDecreaseInPrepaidDeferredExpenseAndOtherAssets_lbl" xlink:role="http://www.xbrl.org/2003/role/totalLabel">Increase (Decrease) in Prepaid Expense and Other Assets, Total</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_IncreaseDecreaseInPrepaidDeferredExpenseAndOtherAssets_lbl" xlink:role="http://www.xbrl.org/2003/role/label">Increase (Decrease) in Prepaid Expense and Other Assets</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_IncreaseDecreaseInPrepaidDeferredExpenseAndOtherAssets_lbl" xlink:role="http://www.xbrl.org/2009/role/negatedLabel">Prepaid expenses and other current assets</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_lbl" xlink:role="http://www.xbrl.org/2003/role/label">Schedule of Share-Based Compensation Arrangements by Share-Based Payment Award [Table]</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_lbl" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Schedule Of Share Based Compensation Arrangements By Share Based Payment Award [Table]</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="dei_EntityIncorporationDateOfIncorporation_lbl" xlink:role="http://www.xbrl.org/2003/role/label">Entity Incorporation, Date of Incorporation</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="dei_EntityIncorporationDateOfIncorporation_lbl" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Entity incorporation date</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingNumber_lbl" xlink:role="http://www.xbrl.org/2003/role/label">Share-Based Compensation Arrangement by Share-Based Payment Award, Options, Outstanding, Number</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingNumber_lbl" xlink:role="http://www.xbrl.org/2003/role/periodEndLabel">Number of Shares, Options outstanding, Ending balance</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingNumber_lbl" xlink:role="http://www.xbrl.org/2003/role/periodStartLabel">Number of Shares, Options outstanding, Beginning balance</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_DebtInstrumentNameDomain_lbl" xlink:role="http://www.xbrl.org/2003/role/label">Debt Instrument, Name [Domain]</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_DebtInstrumentNameDomain_lbl" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Debt Instrument, Name</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="dei_DocumentFiscalYearFocus_lbl" xlink:role="http://www.xbrl.org/2003/role/label">Document Fiscal Year Focus</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="dei_DocumentFiscalYearFocus_lbl" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Document Fiscal Year Focus</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_RepaymentsOfDebt_lbl" xlink:role="http://www.xbrl.org/2003/role/label">Repayments of Debt</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_RepaymentsOfDebt_lbl" xlink:role="http://www.xbrl.org/2003/role/verboseLabel">Repayment of outstanding amount under the loan agreement including fees</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_FuturePolicyBenefitsLiabilityPolicy_lbl" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Liability Related to the Sales of Future Royalties and Non-Cash Interest Expense</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_FuturePolicyBenefitsLiabilityPolicy_lbl" xlink:role="http://www.xbrl.org/2003/role/label">Liability for Future Policy Benefit [Policy Text Block]</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_EarningsPerShareBasic_lbl" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Net loss per share of common stock basic</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_EarningsPerShareBasic_lbl" xlink:role="http://www.xbrl.org/2003/role/label">Earnings Per Share, Basic</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_EarningsPerShareBasic_lbl" xlink:role="http://www.xbrl.org/2003/role/totalLabel">Earnings Per Share, Basic, Total</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_AssetsAbstract_lbl" xlink:role="http://www.xbrl.org/2003/role/label">Assets [Abstract]</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_AssetsAbstract_lbl" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Assets</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_RestrictedCashAssetStatementOfFinancialPositionExtensibleList_lbl" xlink:role="http://www.xbrl.org/2003/role/label">Restricted Cash, Statement of Financial Position [Extensible Enumeration]</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_ProceedsFromIssuanceOfSecuredDebt_lbl" xlink:role="http://www.xbrl.org/2003/role/label">Proceeds from Issuance of Secured Debt</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_ProceedsFromIssuanceOfSecuredDebt_lbl" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Proceeds from royalty purchase and sale agreement</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_PropertyPlantAndEquipmentByTypeAxis_lbl" xlink:role="http://www.xbrl.org/2003/role/label">Long-Lived Tangible Asset [Axis]</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_PropertyPlantAndEquipmentByTypeAxis_lbl" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Long-Lived Tangible Asset</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_LiabilitiesAndStockholdersEquityAbstract_lbl" xlink:role="http://www.xbrl.org/2003/role/label">Liabilities and Equity [Abstract]</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_LiabilitiesAndStockholdersEquityAbstract_lbl" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Liabilities and stockholders&#8217; equity</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_AntidilutiveSecuritiesNameDomain_lbl" xlink:role="http://www.xbrl.org/2003/role/label">Antidilutive Securities, Name [Domain]</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_AntidilutiveSecuritiesNameDomain_lbl" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Antidilutive Securities, Name</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_ProfitLoss_lbl" xlink:role="http://www.xbrl.org/2003/role/totalLabel">Net Income (Loss), Including Portion Attributable to Noncontrolling Interest, Total</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_ProfitLoss_lbl" xlink:role="http://www.xbrl.org/2003/role/label">Net Income (Loss), Including Portion Attributable to Noncontrolling Interest</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_ProfitLoss_lbl" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Net loss</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_AssetsCurrentAbstract_lbl" xlink:role="http://www.xbrl.org/2003/role/label">Assets, Current [Abstract]</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_AssetsCurrentAbstract_lbl" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Current assets:</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_ClassOfWarrantOrRightExercisePriceOfWarrantsOrRights1_lbl" xlink:role="http://www.xbrl.org/2003/role/label">Class of Warrant or Right, Exercise Price of Warrants or Rights</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_ClassOfWarrantOrRightExercisePriceOfWarrantsOrRights1_lbl" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Class of warrant Exercise</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_FairValueMeasurementsFairValueHierarchyDomain_lbl" xlink:role="http://www.xbrl.org/2003/role/label">Fair Value Hierarchy and NAV [Domain]</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_FairValueMeasurementsFairValueHierarchyDomain_lbl" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Fair Value Hierarchy and NAV</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_PayablesAndAccrualsAbstract_lbl" xlink:role="http://www.xbrl.org/2003/role/label">Payables and Accruals [Abstract]</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_IncreaseDecreaseInOperatingCapitalAbstract_lbl" xlink:role="http://www.xbrl.org/2003/role/label">Increase (Decrease) in Operating Capital [Abstract]</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_IncreaseDecreaseInOperatingCapitalAbstract_lbl" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Changes in operating assets and liabilities:</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="dei_CoverAbstract_lbl" xlink:role="http://www.xbrl.org/2003/role/label">Cover [Abstract]</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="srt_ProductsAndServicesDomain_lbl" xlink:role="http://www.xbrl.org/2003/role/label">Product and Service [Domain]</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="srt_ProductsAndServicesDomain_lbl" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Product and Service</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedInPeriod_lbl" xlink:role="http://www.xbrl.org/2003/role/label">Share-Based Compensation Arrangement by Share-Based Payment Award, Equity Instruments Other than Options, Vested in Period</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedInPeriod_lbl" xlink:role="http://www.xbrl.org/2009/role/negatedLabel">Number of Shares, Vested</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_LiabilitiesCurrentAbstract_lbl" xlink:role="http://www.xbrl.org/2003/role/label">Liabilities, Current [Abstract]</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_LiabilitiesCurrentAbstract_lbl" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Current liabilities:</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="srt_MaximumMember_lbl" xlink:role="http://www.xbrl.org/2003/role/label">Maximum [Member]</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="srt_MaximumMember_lbl" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Maximum</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_ProceedsFromIssuanceOfSharesUnderIncentiveAndShareBasedCompensationPlans_lbl" xlink:role="http://www.xbrl.org/2003/role/label">Proceeds, Issuance of Shares, Share-Based Payment Arrangement, Excluding Option Exercised</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_ProceedsFromIssuanceOfSharesUnderIncentiveAndShareBasedCompensationPlans_lbl" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Proceeds from shares issued under employee stock purchase plan</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_ScheduleOfEmployeeServiceShareBasedCompensationAllocationOfRecognizedPeriodCostsTextBlock_lbl" xlink:role="http://www.xbrl.org/2003/role/label">Share-Based Payment Arrangement, Expensed and Capitalized, Amount [Table Text Block]</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_ScheduleOfEmployeeServiceShareBasedCompensationAllocationOfRecognizedPeriodCostsTextBlock_lbl" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Summary of Share-based Compensation Expense</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_NetCashProvidedByUsedInInvestingActivities_lbl" xlink:role="http://www.xbrl.org/2009/role/negatedTotalLabel">Net cash used in investing activities</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_NetCashProvidedByUsedInInvestingActivities_lbl" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Net cash used in investing activities</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_NetCashProvidedByUsedInInvestingActivities_lbl" xlink:role="http://www.xbrl.org/2003/role/totalLabel">Net cash used in investing activities</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_NetCashProvidedByUsedInInvestingActivities_lbl" xlink:role="http://www.xbrl.org/2003/role/label">Net Cash Provided by (Used in) Investing Activities</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_FurnitureAndFixturesMember_lbl" xlink:role="http://www.xbrl.org/2003/role/label">Furniture and Fixtures [Member]</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_FurnitureAndFixturesMember_lbl" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Furniture and Fixtures</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="clsd_FirstCumulativeNetSalesOfProducts_lbl" xlink:role="http://www.xbrl.org/2003/role/documentation">First cumulative net sales of products.</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="clsd_FirstCumulativeNetSalesOfProducts_lbl" xlink:role="http://www.xbrl.org/2003/role/label">First Cumulative Net Sales Of Products</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="clsd_FirstCumulativeNetSalesOfProducts_lbl" xlink:role="http://www.xbrl.org/2003/role/terseLabel">First cumulative net sales of products</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_ScheduleOfAntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareTable_lbl" xlink:role="http://www.xbrl.org/2003/role/label">Schedule of Antidilutive Securities Excluded from Computation of Earnings Per Share [Table]</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_ScheduleOfAntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareTable_lbl" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Schedule Of Antidilutive Securities Excluded From Computation Of Earnings Per Share [Table]</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_AssetAcquisitionAxis_lbl" xlink:role="http://www.xbrl.org/2003/role/label">Asset Acquisition [Axis]</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="clsd_OperatingLeaseFutureMinimumPaymentRemainderOfFiscalYear_lbl" xlink:role="http://www.xbrl.org/2003/role/terseLabel">2022</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="clsd_OperatingLeaseFutureMinimumPaymentRemainderOfFiscalYear_lbl" xlink:role="http://www.xbrl.org/2003/role/label">Operating Lease Future Minimum Payment Remainder Of Fiscal Year</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="clsd_OperatingLeaseFutureMinimumPaymentRemainderOfFiscalYear_lbl" xlink:role="http://www.xbrl.org/2003/role/documentation">Operating lease future minimum payment remainder of fiscal year</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_StockIssuedDuringPeriodSharesStockOptionsExercised_lbl" xlink:role="http://www.xbrl.org/2003/role/label">Share-Based Compensation Arrangement by Share-Based Payment Award, Options, Exercises in Period</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_StockIssuedDuringPeriodSharesStockOptionsExercised_lbl" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Exercise of stock options, shares</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_StockIssuedDuringPeriodSharesStockOptionsExercised_lbl" xlink:role="http://www.xbrl.org/2009/role/negatedLabel">Number of Shares, Exercised</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_FairValueInputsLevel3Member_lbl" xlink:role="http://www.xbrl.org/2003/role/label">Fair Value, Inputs, Level 3 [Member]</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_FairValueInputsLevel3Member_lbl" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Level 3</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_UseOfEstimates_lbl" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Use of Estimates</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_UseOfEstimates_lbl" xlink:role="http://www.xbrl.org/2003/role/label">Use of Estimates, Policy [Policy Text Block]</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_DebtInstrumentBasisSpreadOnVariableRate1_lbl" xlink:role="http://www.xbrl.org/2003/role/label">Debt Instrument, Basis Spread on Variable Rate</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_DebtInstrumentBasisSpreadOnVariableRate1_lbl" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Variable interest rate</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="clsd_SiliconValleyBankMidCapFundingIIITrustAndMidCapFinancialTrustMember_lbl" xlink:role="http://www.xbrl.org/2003/role/documentation">Silicon Valley Bank, MidCap funding III trust and MidCap financial trust.</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="clsd_SiliconValleyBankMidCapFundingIIITrustAndMidCapFinancialTrustMember_lbl" xlink:role="http://www.xbrl.org/2003/role/label">Silicon Valley Bank Mid Cap Funding I I I Trust And Mid Cap Financial Trust [Member]</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="clsd_SiliconValleyBankMidCapFundingIIITrustAndMidCapFinancialTrustMember_lbl" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Silicon Valley Bank, MidCap Funding III Trust and MidCap Financial Trust</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_FairValueAssetsMeasuredOnRecurringAndNonrecurringBasisTableTextBlock_lbl" xlink:role="http://www.xbrl.org/2003/role/label">Fair Value, Assets Measured on Recurring and Nonrecurring Basis [Table Text Block]</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_FairValueAssetsMeasuredOnRecurringAndNonrecurringBasisTableTextBlock_lbl" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Summary of Assets Measured at Fair Value</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="clsd_OperatingLeaseImputedInterest_lbl" xlink:role="http://www.xbrl.org/2003/role/documentation">Operating Lease Imputed interest.</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="clsd_OperatingLeaseImputedInterest_lbl" xlink:role="http://www.xbrl.org/2003/role/label">Operating Lease Imputed Interest</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="clsd_OperatingLeaseImputedInterest_lbl" xlink:role="http://www.xbrl.org/2009/role/negatedLabel">Less imputed interest</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_StockIssuedDuringPeriodValueStockOptionsExercised_lbl" xlink:role="http://www.xbrl.org/2003/role/label">Stock Issued During Period, Value, Stock Options Exercised</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_StockIssuedDuringPeriodValueStockOptionsExercised_lbl" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Exercise of stock options</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="clsd_NonCashInterestExpenseOnLiabilityRelatedToTheSalesOfFutureRoyalites_lbl" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Non-cash interest expense</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="clsd_NonCashInterestExpenseOnLiabilityRelatedToTheSalesOfFutureRoyalites_lbl" xlink:role="http://www.xbrl.org/2003/role/label">Non-cash interest expense on liability related to the sales of future royalites</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="clsd_NonCashInterestExpenseOnLiabilityRelatedToTheSalesOfFutureRoyalites_lbl" xlink:role="http://www.xbrl.org/2003/role/documentation">Non-cash interest expense on liability related to the sales of future royalites</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_PropertyPlantAndEquipmentUsefulLife_lbl" xlink:role="http://www.xbrl.org/2003/role/label">Property, Plant and Equipment, Useful Life</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_PropertyPlantAndEquipmentUsefulLife_lbl" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Estimated Useful Lives (Years)</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="clsd_NonVestedRestrictedStockUnitsMember_lbl" xlink:role="http://www.xbrl.org/2003/role/label">Non Vested Restricted Stock Units [Member]</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="clsd_NonVestedRestrictedStockUnitsMember_lbl" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Non-vested Restricted Stock Units</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="clsd_NonVestedRestrictedStockUnitsMember_lbl" xlink:role="http://www.xbrl.org/2003/role/documentation">Non vested restricted stock units.</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_CommonStockSharesAuthorized_lbl" xlink:role="http://www.xbrl.org/2003/role/label">Common Stock, Shares Authorized</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_CommonStockSharesAuthorized_lbl" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Common stock, shares authorized</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_CommonStockSharesAuthorized_lbl" xlink:role="http://www.xbrl.org/2003/role/verboseLabel">Common stock, shares authorized</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="dei_TradingSymbol_lbl" xlink:role="http://www.xbrl.org/2003/role/label">Trading Symbol</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="dei_TradingSymbol_lbl" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Trading Symbol</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_InterestExpenseMember_lbl" xlink:role="http://www.xbrl.org/2003/role/label">Interest Expense [Member]</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_InterestExpenseMember_lbl" xlink:role="http://www.xbrl.org/2003/role/verboseLabel">Interest Expense</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_SubsequentEventTypeAxis_lbl" xlink:role="http://www.xbrl.org/2003/role/label">Subsequent Event Type [Axis]</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="clsd_OperatingLeaseFutureMinimumPaymentDueInTwoYears_lbl" xlink:role="http://www.xbrl.org/2003/role/terseLabel">2023</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="clsd_OperatingLeaseFutureMinimumPaymentDueInTwoYears_lbl" xlink:role="http://www.xbrl.org/2003/role/label">Operating Lease Future Minimum Payment Due In Two Years</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="clsd_OperatingLeaseFutureMinimumPaymentDueInTwoYears_lbl" xlink:role="http://www.xbrl.org/2003/role/documentation">Operating lease future minimum payment due in two years</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_AccountsPayableCurrent_lbl" xlink:role="http://www.xbrl.org/2003/role/totalLabel">Accounts Payable, Current, Total</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_AccountsPayableCurrent_lbl" xlink:role="http://www.xbrl.org/2003/role/label">Accounts Payable, Current</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_AccountsPayableCurrent_lbl" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Accounts payable</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_PlanNameAxis_lbl" xlink:role="http://www.xbrl.org/2003/role/label">Plan Name [Axis]</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_PlanNameAxis_lbl" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Plan Name</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_DebtInstrumentPeriodicPaymentInterest_lbl" xlink:role="http://www.xbrl.org/2003/role/label">Debt Instrument, Periodic Payment, Interest</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_DebtInstrumentPeriodicPaymentInterest_lbl" xlink:role="http://www.xbrl.org/2003/role/verboseLabel">Debt Instrument, Final Payment, Interest</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_PropertyPlantAndEquipmentTypeDomain_lbl" xlink:role="http://www.xbrl.org/2003/role/label">Long-Lived Tangible Asset [Domain]</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_PropertyPlantAndEquipmentTypeDomain_lbl" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Long-Lived Tangible Asset</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_CommonStockParOrStatedValuePerShare_lbl" xlink:role="http://www.xbrl.org/2003/role/label">Common Stock, Par or Stated Value Per Share</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_CommonStockParOrStatedValuePerShare_lbl" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Common stock, par value</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_CommonStockParOrStatedValuePerShare_lbl" xlink:role="http://www.xbrl.org/2003/role/verboseLabel">Common stock, par value</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_VariableLeaseCost_lbl" xlink:role="http://www.xbrl.org/2003/role/label">Variable Lease, Cost</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_VariableLeaseCost_lbl" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Variable Lease, Cost</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="clsd_SecondMilestoneProceedsFromRoyaltyPurchaseAndSaleAgreement_lbl" xlink:role="http://www.xbrl.org/2003/role/label">Second Milestone Proceeds From Royalty Purchase And Sale Agreement</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="clsd_SecondMilestoneProceedsFromRoyaltyPurchaseAndSaleAgreement_lbl" xlink:role="http://www.xbrl.org/2003/role/documentation">Second Milestone Proceeds From Royalty Purchase And Sale Agreement</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriod_lbl" xlink:role="http://www.xbrl.org/2003/role/label">Share-Based Compensation Arrangement by Share-Based Payment Award, Equity Instruments Other than Options, Grants in Period</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriod_lbl" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Number of Shares, Granted</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_PropertyPlantAndEquipmentDisclosureTextBlock_lbl" xlink:role="http://www.xbrl.org/2003/role/label">Property, Plant and Equipment Disclosure [Text Block]</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_PropertyPlantAndEquipmentDisclosureTextBlock_lbl" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Property and Equipment, Net</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_PropertyPlantAndEquipmentEstimatedUsefulLives_lbl" xlink:role="http://www.xbrl.org/2003/role/label">Property, Plant and Equipment, Estimated Useful Lives</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_PropertyPlantAndEquipmentEstimatedUsefulLives_lbl" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Estimated Useful Lives (Years)</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardOptionsGrantsInPeriodWeightedAverageExercisePrice_lbl" xlink:role="http://www.xbrl.org/2003/role/label">Share-Based Compensation Arrangements by Share-Based Payment Award, Options, Grants in Period, Weighted Average Exercise Price</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardOptionsGrantsInPeriodWeightedAverageExercisePrice_lbl" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Weighted Average Exercise Price, Granted</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="clsd_SecondAmendedAndRestatedLoanAndSecurityAgreementMember_lbl" xlink:role="http://www.xbrl.org/2003/role/documentation">Second amended and restated loan and security agreement.</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="clsd_SecondAmendedAndRestatedLoanAndSecurityAgreementMember_lbl" xlink:role="http://www.xbrl.org/2003/role/label">Second Amended And Restated Loan And Security Agreement [Member]</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="clsd_SecondAmendedAndRestatedLoanAndSecurityAgreementMember_lbl" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Second Amended and Restated Loan and Security Agreement</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_LongTermDebtTextBlock_lbl" xlink:role="http://www.xbrl.org/2003/role/label">Long-Term Debt [Text Block]</link:label>
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    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="clsd_InitialProceedsFromRoyaltyPurchaseAndSalesAgreementNetOfCertainExpenses_lbl" xlink:role="http://www.xbrl.org/2003/role/label">Initial Proceeds From Royalty Purchase and Sales Agreement Net of Certain Expenses</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="clsd_InitialProceedsFromRoyaltyPurchaseAndSalesAgreementNetOfCertainExpenses_lbl" xlink:role="http://www.xbrl.org/2003/role/documentation">Initial proceeds from royalty purchase and sales agreement net of certain expenses.</link:label>
    <link:label xml:lang="en-US" xlink:type="resource" xlink:label="us-gaap_DebtInstrumentLineItems_lbl" xlink:role="http://www.xbrl.org/2003/role/label">Debt Instrument [Line Items]</link:label>
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